Chest Monster



""Computer roleplaying games often have mimics... which are always disguised as chests. Chest chest chest. It makes you wish that digital orcs would stick their electrum pieces in a foot locker or some variety of credenza, just to break the ennui of another piratey-looking wooden chest suddenly sprouting limbs and beating you to within an inch of your save file. It would be refreshing like the breezes of summer to be able to say 'Hey! I just had my clavicle shattered by an aluminum tool shed!'""

- Lore Sjoberg, The Book of Ratings, D&D Monsters, Part 2

Adventuring's hard enough -- you've got Everything Trying to Kill You, brain-wracking puzzles, hazardous environments, and, if you're unlucky, the interface itself.

And now, the loot wants in on the action.

A Chest Monster is an enemy or hazard that has disguised itself to look like something positive: a power-up, an ally, a Save Point, or -- in the archetypical example -- a treasure chest. They are frequently called "mimics" for this reason, and are generally stronger (sometimes much stronger) in battle than the surrounding Mooks in the area. Sometimes they are ordinary chests with a monster locked inside. It may or may not be possible to escape from a Chest Monster once it's been disturbed -- you either defeat it, or die trying.

Obviously, chest monsters aren't threatening at all if you can avoid triggering them in the first place, but in games that encourage you to always open every last treasure chest in sight, this is easier said than done. It may or may not be possible to identify a Chest Monster without opening it up and springing the trap -- sometimes there may be a minor flaw or difference that allows you to tell them apart from the genuine article; sometimes you can use an item or ability to analyze it and tell if it's real. Other times the placement is a clue -- if a power-up is right there in plain sight with no guards or obstacles protecting it, it might be a trap. Or not. If all else fails and there are no clues, you'll just have to find out the hard way and hope it doesn't bite back.

It makes you wonder; where did these things come from? Did a wizard make them, or have people in the D & D world been putting chests in dungeons so long mimics have had time to evolve to fill this niche?

Sometimes you will get something of value if you beat the Chest Monster. See also Inexplicable Treasure Chests, Inn Security, and Alluring Anglerfish.

Compare Poison Mushroom, which is a harmful item disguised as a beneficial one, and Wall Master, which is an enemy that hides in and/or disguises itself as the scenery.

Not to be confused with Chest Burster. Unrelated to Boob Bite, or a metaphor from the 6th Harry Potter novel. Has nothing to do with anyone's endowment.

Anime and Manga

 * An episode of Rune Soldier Louie has a short fight scene with the party attacked by a door mimic, as well as a traditional treasure chest mimic.
 * One Piece has this during and episode in the Thriller Bark arc where Nami opens a chest and a surprise zombie pops out.
 * Much, much earlier, Luffy and Nami encounter a little man who, twenty years before, had fallen into a treasure chest and couldn't get out. He tries to invoke this trope to scare people away from his island.

Card Games

 * The Yu-Gi-Oh Card Game has a reference to this in the form of Dark Mimic LV1 and Dark Mimic LV3, who both look like chests and give the player an extra draw when activated.
 * They even act as a traditional Chest Monster in Yu-Gi-Oh World Championship Tournament 2008. In the Pyramid in the World of Sunlight, there is occasionally a treasure chest. it will give you GP, a card... or a challenge by Dark Mimic Lv1.
 * Other cards also allude to this, such as Yaranzo (classic demon in a treasure box) and Stuffed Animal (demon teddy bear), as well as the Man-Eating Treasure Chest.
 * Hungry Burger fits this trope as well.

Literature

 * While not an enemy of the protagonist, the Luggage from the Discworld novels is still a ravenous chest monster. But it does its master's laundry. It is, however, quite harmful to everyone else. It can also be distinguished from, say, the sort of luggage to steal underwear from, by the feet underneath. And the fact that it will, without eyes, look at you in a very unfriendly manner.
 * It is, in fact, made of Sapient Pearwood and the inside is much, much bigger than the outside. It's also fiercely protective of its owner, as many a poor schmuck finds out, and will follow him anywhere in time or space, including the most grisly and esoteric of Eldritch Locations. Don't mess with the Luggage.
 * Not just anywhere in time and space. Just plain anywhere, including another universe in which magic doesn't exist or function.
 * The Luggage will literally follow you to Hell and back. And inside your own mind.
 * In Dougal Dixon's After Man, the oakleaf toad is this trope for smaller invertebrate-eating animals. Camouflaged by the leaf-like appearance of its body, it lures in prey such as shrews or small birds with its tongue, which resembles an earthworm.

Live Action TV

 * Parodied with the paedophile disguised as a school in Brass Eye.

Real Life

 * The old snake-in-the-can-of-nuts prank is a popular real life example.
 * The mata-mata, a South American variety of snapping turtle, does a variation on this; it sits perfectly still on the riverbed, with its mouth open and its tongue wiggling. When a fish comes to check out what it thinks is a nice worm to eat, the turtle swallows the fish.
 * The monkfish a species of flat angler fish that hides in the sea floor buried in the sand, it waves a lure to attract unsuspecting fish, and when it gets close enough it jumps out of the sand and gobbles it down.

Tabletop Games

 * The great-granddaddy of this trope is the mimic, a blobby monster in Dungeons and Dragons that could imitate any stone or wood item; the artwork in the first edition Monster Manual depicted one in the shape of a chest, setting the mold to be followed in its videogame descendants. Incidentally, it's capable of making anything it touches stick to it as if glued and thereby making sure whoever touches it first is out of the fight. The second edition compounded the problem by adding a variant that can grow to the size of a building, inflicting a Total Party Kill on any group unfortunate enough to enter the "dungeon." (It's common DM practice to have that type pose as a gazebo.)
 * There's also the "bag of devouring", a fake Bag of Holding that's actually the mouth of an extradimensional predator, which may or may not be asleep.
 * The 3rd edition Epic Level Handbook has the living vault which, in addition to containing valuables, is a powerful creature.

Video Games

 * The 7th Saga has Tricks. They're some of the hardest enemies in the game when you fight them, and that's saying something. They randomly drop a variety of gemstones, and with some Save Scumming, the player can acquire a hoard of emeralds and sapphires.
 * Banjo-Kazooie:
 * The first game has literal chest monsters in Treasure Trove Cove.
 * Banjo-Tooie has fake Jinjos called Minjos. They look exactly like the Jinjos, but they will try to attack you if you get near. To add to the confusion, they are often hidden in out-of-the-way places like the regular Jinjos.
 * Tooie also has the boss Mingy Jongo, the robotic "Crafty Shaman Impersonator" who appears in one of the two identical homes of the friendly shaman Mumbo Jumbo in the last major world. Distinct from the original because he drops the genuine article's Hulk Speak. Must be seen to believed. The way you can tell the difference between the two is that
 * The old Namco game Baraduke had the blue "Octy" monsters release a treasure capsule which would randomly contain nothing, a gem for score, a friendly alien for the bonus games, a weapon upgrade and an angry Pacmanesque purple monster. Alas, it was require to touch the capsules to open them, always prompting you to run away after doing so!
 * Literal chest monsters in the Treasure Desert world of Bubble Symphony. Which are also named Mimic.
 * The 2D Castlevanias have chest monsters that look slightly different from normal chests. Symphony of the Night has an optional save point boss.
 * Portrait of Ruin has chest Mimics - but no chests.
 * The Succubus in Aria of Sorrow disguise herself as Soma's friend and love interest Mina Hakuba, only shedding the disguise (and clothes!) when attacked or you get too near.
 * Succubi in Dawn of Sorrow disguised themselves as Yoko Belnades instead, and didn't bother to shed their disguises before they attacked you - they'd just whip around as you went by and put a boot square in your ass. It then poked fun at the fact that neither disguise fooled many players by having one room that was just a long hall with multiple pre-disguised Succubi lined up in a row.
 * Order of Ecclesia has fake chests that are even worse due to the abundance of chests in the game compared to other games.
 * They become hilarious when you play Albus Mode. In that mode, all treasure chests are removed except for two kinds: fancy chests, which hold life, magic and heart increasers... and Mimics, now the only wooden chests in the game. It's pretty easy to avoid them in this mode, needless to say.
 * Symphony of the Night also had a fake Save Point. In one room is a real save point (which, in this game, are coffins) and, just across the hall, is another room that looks like a different-colored save point, but will in fact trigger a battle with a succubus.
 * Vampire Killer had trap candles that released slimes when whipped.
 * Cave Story does it with a killer door in the first dungeon. Not fun to be killed by, but tons of more fun to see your friends not notice its evil red eyes and try to walk through it.
 * Cave Story also has unused data for a literal chest monster, as well as animate versions of jars and Save Points.
 * Saga Frontier featured evil chests that spawned monsters. However, a lot of them dropped awesome prizes when defeated, so if you knew which were booby-trapped, you could grind and then go kick the chest's butt for loot.
 * Chrono Cross and Chrono Trigger had save point monsters.
 * As for Chrono Trigger, aside from the actual save points that were monster, at least one other save point triggered a battle because the monsters nearby heard the "ding". 
 * One of the most frustrating enemies in the PC game Dgeneration was the C/Generation, a shapeshifting monster that likes to disguise itself as everyday objects like chairs, power-ups, and the people that you're supposed to be rescuing. They're also immune to your primary weapon.
 * Both Dark Cloud games had Mimics. There's also King Mimics, which are bigger and stronger.
 * In Doom 3 numbered lockers typically contain goodies. However, woe is you if you open locker #666.
 * The Donkey Kong Country games had enemies that hid in barrels. The most common type would just knock you around, but the ones that hid in TNT barrels were fatal.
 * It went further than that in Donkey Kong Country 2; yellow ones stole bananas from you with each bump, while the black ones with a Jolly Roger on them will rob you of extra lives.
 * In Dragon Slayer, treasure chests would sometimes contain Shinigami that followed you around and prevented spellcasting.
 * The Dragon Quest series, which, if not the Trope Maker, is at least the popularizer. It started the idea of always being a chest.
 * VII mixed things up a bit with monsters disguised as pots, books, and wine bottles. The only destroyable objects missing a monster were barrels.
 * Dragon Quest VIII has a Chest Monster boss.
 * Dragon Quest Heroes: Rocket Slime has a cute variant of the standard Chest Monster.
 * Duke Nukem and Duke Nukem II had chests that, while not technically monsters, had bombs inside that exploded after the chest was shot. In Duke Nukem II, these could be distinguished from chests containing health items by walking: if you passed in front of the chest, it contained health; if you passed behind it, it was a bomb. Careful level design made this nearly impossible to notice until it was revealed in the hints file for the registered version.
 * Duke Nukem 3D features a variation: the trashcans throughout the game can be broken and they will provide you with power-ups. But later in the game, some of the trashcans contain hidden monsters, and there's no way of telling which ones do and which ones don't until you smash them open...
 * Dungeon Siege 2 had Mimics that were nightmarish. They were uncommon but unbelievably dangerous. Luckily they did drop a bunch of good loot.
 * The Final Fantasy series. These are sometimes called "enemy ambush" or "monster in a box", and most of them do give you items upon their defeat, often very valuable ones.
 * Final Fantasy IV's most memorable example is probably that box with the three Mad Ogres in it.
 * Final Fantasy V had a monster guarding the Save Point in The Very Definitely Final Dungeon, right before the final boss.
 * The most infamous Chest Monster has to be Shinryu, a Bonus Boss in Final Fantasy V. Its tougher version in the GBA remake also hides in one.
 * While VI generally has its monsters hiding in boxes (even when its monsters are much too large to reasonably fit), one optional miniboss triggered by a chest is identified as an "angler welk," a gigantic snail-like creature with a chest attached to it like the glowing portion of an angler fish.
 * Final Fantasy Tactics a 2 has chests that sometimes are Mimics (White Gloves monsters) in disguise. They even get a surprise attack on the person that tried to open the chest. Afterwards, they act like a normal enemy and drop loot, which is usually more valuable than the potion or antidote commonly found in those chests (the more valuable chests look different and are never Mimics). They aren't much of a threat either, as they don't have a lot of health and are vulnerable to magic.
 * Final Fantasy VIII has an NPC monster in Esthar.
 * Mimics also make an appearance in Final Fantasy IX as 'monster-in-the-box' enemies (of course, this time the monster is the box).
 * Final Fantasy X 's Omega Ruins occasionally pits you in Random Encounters with Mimics, which if stolen from will reveal one of their four possible forms. Oh, and this happens, you can't escape from battle until you defeat it.
 * They do drop a lot of Gil though. You can safely Mug them though, if it's not a real treasure, it'll still die before becoming a Mimic.
 * Final Fantasy XII, in any area where the treasure chests looked like round pots with four metal legs, some of them would of course turn out to be actual mimics. The game's monster lore provided a long, creative backstory regarding their creation. And then there are the "Crystalbugs", three monsters disguised as Save Points, which were impervious to all elements and attacked using high-level spells, but fortunately left actual Save Points behind upon their defeat.
 * Dissidia Final Fantasy technically doesn't have Chest Monsters. But due to the board-game type mechanics, when you pick up an item or defeat an enemy, other items/enemies will often appear in the stage. So pretty much any time you see a chest, you can be sure opening it will cause an enemy to spawn behind you and attack. They don't even try to hide it in one of the final stages - the path to the boss's square is clear and you can walk right up to it and end the stage instantly, or you can open the single treasure chest in the middle of the stage with no enemies around it...not until you open it anyway. When you do, four enemies appear, all very high level, and ambush you. There is no way a player can look at that stage and not know what's gonna happen if they go for the chest.
 * Final Fantasy XI has treasure chests and coffers that are normally opened with Interchangeable Antimatter Keys. Thieves have a special ability to open them without a key, but that creates a chance that the chest/coffer will turn out to be a mimic. There's also a boss battle where you're confronted with three chests. One is an actual chest while the other two are mimics. Choose the real chest and you get the loot without a fight. Try to open one of the mimics and you'll have to fight both of them (or give up on the treasure and beat feet).
 * In Fire Emblem: The Sealed Sword, two of the treasure chests in a Gaiden chapter contain fire Mamkutes.
 * The Flying Giftbox monster from zOMG looks identical to the Magical Giftboxes that have randomly rewarded Gaians with rare items for years. But get too close and they'll attempt to eat you. Flying Giftboxes can talk, and tend to travel in groups. The real threat comes from the Ring Box, which is the Metal Slime version of the Giftbox. It also looks identical to a Magical Giftbox, but travels alone and does not speak, making it easier to mistake for an actual giftbox if you aren't familiar with their weaker cousins. (Ironically, there actually are Chests, Baskets, and Boxes in the game, and they all are Animated as well, but the only hostile thing they do is refuse to open until all of other the Animated on the screen are dispatched. However, there are certain chests that have Animated pop out of them; you get the reward after they're defeated.)
 * Gauntlet has chests throughout the game that you open using keys you pick up along your way. Most of these chests contain food, money, or power-ups. But some of them have a ticking bomb inside them that cause damage to you if you are anywhere near it when it goes off. It also ruins any food or items that are in its range when it explodes, so if you set on off before you collect all the useful things around it you basically have two choices: Run around and collect the things and take the damage, or run away from the area and say goodbye to the items but take no damage. However, these chests are always in the same places, so if you have completed the level before and you remember which ones have bombs in them, you can avoid them or use them to your advantage to attack nearby monsters.
 * The original Diablo and its sequel had destructible barrels with a high chance of containing an enemy skeleton instead of loot. Diablo III carries on the tradition, as well as having skeletons hide under lootable floor tiles and who knows what else.
 * Golden Axe Warrior.
 * The Ghosts N Goblins series had many of these, including living treasure chests, beartraps, and magicians who turned Arthur into a frog other other creature.
 * Spiritual successor Maximo has mimics which look like treasure chests with giant teeth and wizards hiding in chests which will turn you into an old man or baby if they hit you with their spells.
 * In Golden Sun, the Mimics actually drop some good items, so it is worth it to in engage them even if you are aware they are traps.
 * When first encountered, their huge well of HP is rather annoying, as it takes forever to kill them. this tends to balance out later in the game, when you can kill them rather quickly and easily.
 * The original Half Life had its own variation, a single first-aid station out of dozens throughout the game will explode if one tries to use it. It is conspicuous because it's sparking, but the temptation to heal up (or top off) after an intense battle just previously oft proves too great.
 * In the second Harry Potter video game, the occasional chest will turn out to contain Peeves the Poltergeist instead of useful items. This will not happen until the Skurge Challenge, though, where you're being tested on a spell that can be used to scare him off, so it could be considered part of the training. There's also a gnome in a chest in the Forbidden Forest level.
 * The freeware Platform Hell game I Wanna Be the Guy had a killer save point right before the final boss. It would turn into a regular save point upon being killed.
 * It still appears in Impossible mode, which is supposed to have no save points. The save monster disappears after being killed, but there's a 1 frame delay in which it's a normal save point that can actually be used. Good Bad Bugs, indeed.
 * Kingdom Hearts features this in the very last dungeon: You have to run from chest to chest to move on, because invisible walls are blocking every other path. Of course, every player has the great urge to open these chests, so a quarter of them are actually filled with The Heartless. To make matters worse this is the only part of the game where you CAN'T run from random encounters! On the other hand, each of these encounters does give you a good item when you beat it.
 * "Kingdom Hearts: Chain of Memories" had a better one- a treasure room called False Bounty. Three chests, but only one has treasure. Open either of the other two, you get a random fight.
 * In all three games we have Barrel Spiders and Pot Spiders. Barrels and pots usually dispense health and magic orbs when hit, but come close to these guys and they'll sprout eyes and legs and start attacking you as well as blowing themselves up.
 * And then Jafar comes along and conjures up a Barrel Centipede! What an asshole!
 * Kingdom Hearts Birth By Sleep has 'Chest Spiders,' which are Exactly What It Says On the Tin.
 * Kingdom Hearts 358 Days Over 2 has the Cymbal Monkey and its stronger form, the Tricky Monkey, which hide in fake treasure chests where one would normally find items.
 * Lampshaded in the browser-based MMO Kingdom of Loathing, where smashing a barrel in the Barrel Full of Barrels will sometimes result in a combat encounter with a mimic. The narrator even exclaims before the fight "What the? You thought these things could only mimic chests!"
 * There's also a mimic you fight who was disguised as "something that looks like a cloak" (for which you pay 5000 local currency units directly prior to engaging in combat); after combat, you use the dead mimic's body to get either a transformation wand or a set of potions and a ring.
 * In La-Mulana, the Twin Labyrinths has a fake Ankh Jewel that turns into a bunch of Goddamned Bats when approached. However, a similar bat explosion results when a necessary passage in the Temple of Moonlight is opened up.
 * The Legend of Zelda:
 * In The Legend of Zelda Ocarina of Time's Spirit Temple, you're conditioned for most of the dungeon to believe that "reflecting light onto sun switches = good". However, a handful of these switches release booby trapped chests that freeze Link upon being opened and invisible Floor Masters when tripped. The Fire Temple includes a few door monsters that fall down on top of you when you try to open them. Also appearing in several dungeons throughout the game are pots that, while not "fake" per se (they often contain the same minor items as normal pots), rise up off the ground and hurl themselves at you.
 * Earlier, in 1992, The Legend of Zelda Links Awakening features treasure chests that look normal but release Zols when opened. Thankfully, these are somewhat rare.
 * The Legend of Zelda a Link To T He Past do this with skulls (the Dark World's equivalent of rocks) and dungeon tiles coming to life. It also places mines and enemies under some bushes.
 * In The Legend of Zelda Phantom Hourglass, you can occasionally come across rupees just sitting out in the open. These are attached to an antenna on a Like Like (monsters that look like a giant blancmange with a maw on top) that would pop out of the ground and try to suck you in if you get close enough. These were first introduced as Rupee Likes in the Oracle series.
 * In The Legend of Zelda Twilight Princess there are giant worms which hid under floor tiles and jump up when you cross them. Luckily, they occasionally peek up to look around, and you can wait with the Gale Boomerang in tow.
 * Zelda II the Adventure of Link also occasionally has townspeople who turn into monsters after you talk to them. These are fairly easy to avoid, though- just... don't talk to the random townspeople. They very rarely have anything interesting to say anyway.
 * The Legend of Zelda Spirit Tracks takes the familiar Like-Like enemy and makes it infinitely more frustrating by including ones that hide inside pots and burst out to attack you when you get too close. Pots containing them will occasionally shake, tipping you off to the shield-eating menace's presence, but chances are that you'll be either too busy or too eager to get whatever's inside the pot to notice. And then there's the one hidden inside an actual treasure chest. Fortunately, this only happens once.
 * There are also the Armos statues throughout the series. Some attack, some don't.
 * In The Wind Waker, sometimes small enemies burst out of jars.
 * In Lufia II. Red and blue chests are both mimicked, to annoying effect in the game's bonus dungeon. Both are distinguishable from the genuine article by their coloring being slightly off, but the blue mimics are much harder to pick out than the red ones, and if you get caught by one, unless you've really geared and leveled up well (read: went in with more than a few items from, well, blue chests and/or gotten really lucky), your ass is pretty much grass.
 * Mabinogi has monsters called Mimics, which look exactly like chests in the dungeon they appear in. Every room (or section of corridor) with more than one chest means that all but one is a mimic. And the fomor scrolls they commonly drop are quite lucrative. Unlike most examples on this page, these mimics are fun to encounter!
 * The Mario Kart series features Fake Item Boxes as a recurring item. They differ from regular item boxes only in that their signature "?" insignia is upside down. However, in the DS version, they also show up clearly different on the minimap, and after 64, are colored red.
 * They could however, be nasty surprises if well-camouflaged in a group of regular item boxes, even making racers other than the victim suffer as they would waste item boxes during the recovery time.
 * Even Mega Man is not immune.
 * Mega Man and Bass has literal Treasure Chest Monsters, in Pirate Man's level. There are also legitimate chests containing the CDs needed for One Hundred Percent Completion.
 * Mega Man ZX Advent has the Vitaful, which looks like one of those capsules you pick up to fully replenish your health, only purple in coloration. They also stop flashing before they reveal their true nature, which happens when you get too close.
 * A few One Ups in the later levels of Mega Man 9 are actually Metools in disguise. To make matters worse, it appears among a real one-up and some other goodies in an After Spike Gauntlet Recovery area. They're less likely to fool you when they appear in Endless Attack, since it's a mode where you only get 1 life.
 * Mega Man Legends had false treasure chests that would fire bombs at you when you opened them. Some even grew legs and started running! To add insult to injury one particular chest looked like it would be something you could money farm off of, it would stand up and generate a massive amount of refractor shards and dump them right in front of you...try to get them without the vacuum though and it would try to sucker shoot you with a single bomb!
 * Metroid:
 * In Metroid Fusion, an X parasite mimics one of the Chozo statues that traditionally power Samus up. Two more X mimic missile and energy tank Power Ups.
 * In Super Metroid, several Chozo statues come to life and try to kill you after you take their power ups from them. It's not clear if this is a result of the Chozo's becoming more warlike as they were forced to fight the Space Pirates, or if it's a trap set up by the Space Pirates specifically to try to kill Samus.
 * Metroid II: Return of Samus has Arachnus, an optional boss disguising itself as an item held by a Chozo statue. It can only be harmed by bombs and yields the Spring Ball after killing it.
 * The Boost Ball power-up in Metroid Prime 3: Corruption leads you to a boss battle against the Defense Drone when you approach it. You do get it after the battle, though.
 * Mother 3 has just one chest monster, but a few boxes in a haunted castle that don't contain enemies as such, but do contain ghosts that cause a specific status ailment.
 * Other boxes are even more pointless: some boxes set off fireworks, others cause little drum licks to play, and a few simply fart at you. To this, the game only responds: "...Ah. Lucas opened the present". Incredibly enough, there was a hot spring in the box!" Considering the fact that you have to get in a hot spring to be healed by it...
 * Also, the lethal-on-contact Ultimate Chimera in a bathroom.
 * Among the monsters there are also door mimics, slightly different from real doors.
 * There's also a Men's Room Sign enemy, which imitates a...men's room sign.
 * In Nethack, mimics are most commonly found in shops, which makes a nasty trap for lower level characters. They rarely ever imitate the correct item type, making for a fun little minigame of "find the odd symbol out" with, say, an ! (potion) icon in a rare book shop full of + (spellbooks). Won't help in a general store, however.
 * Unless they mimic, say, the stairs up or down. Or the ] symbol ([ is armor, but ] is unused).
 * Neverwinter Nights had a funny one, either in one of the expansion packs or the official mods.
 * In the Xbox 360 game Ninja Gaiden II, boxes are scattered all over the place, which usually give you some kind of health boost or extra essence. But every so often, it contains zombie fish which can seriously hurt you if you're not careful. This is actually carried over from the first game in the series, back on the Xbox.
 * The Mimics in Nox.
 * Such creatures are briefly encountered in the Ghost Ship portion of Okami. Fortunately, their coloration and a certain wind power can give away their disguise.
 * The Hurt Plants of Paper Mario look like Heart Plants. But while Heart Plants provide you with Heart Points, Hurt Plants initiate battles with you.
 * The sequel featured a parody of this trope by including large black chests holding slumbering evil spirits. Every time you opened one the spirit inside would place a curse on you, but the effect would invariably end up being a useful in-game ability.
 * Perfect Dark featured the Dragon machine gun, which had a secondary mode that allowed you to turn it into a proximity mine. This was tons of fun in deathmatches. ("Hey, I think I'll stroll over here and grab this gun...What the...!?")
 * Persona 4 hides Bonus Boss Reaper in random treasure chests while playing through a New Game Plus. Thankfully, it's kind enough to give you an ambiguous warning when you try to open it.
 * Phantasy Star II has a dead-end room in the final dungeon where a single treasure chest blocks your path. After navigating a maze dungeon with powerful monsters, one would imagine this implies the part where you get the final ultimate item you can use to reach or defeat the final boss; however, it turns out to be one doozy of a Chest Monster...
 * In the original Phantasy Star, the treasure chests dropped after Random Encounters were occasionally boobytrapped to explode or shoot an arrow when they were opened.
 * Pokémon. The field sprites used for item balls are identical to the Mons Voltorb and Electrode. Said Pokémon have a nasty tendency to explode before you can KO them.
 * This completely stopped making sense in Generation III. Prior to that, the sprite for item balls and the Voltorb/Electrode were just balls with red and white hemispheres. From Gen. III onwards, the sprite is very clearly a Poké Ball shape with a button in the center, which both Voltorb and Electrode lack.
 * On the route just east of Fallarbor Town in Pokemon Ruby/Sapphire/Emerald, dimples in the layer of volcanic ash can mean one of two things; a hidden item, or a disguised Ninja Boy who will leap out, say something ridiculous, and proceed to poison all of your Pokemon with the inevitable Koffing.
 * Item Boxes in Colosseum and XD are square in shape, so Genius Sonority knew they couldn't use the old Fake Item Ball trick from the games. They still included their own brand of Paranoia Fuel with ceiling-mounted Cipher Peons, which were placed in otherwise empty hallways and love to drop in your path when you desperately needed to get to the healing machine they were most likely guarding.
 * Foongus and Amoongus - mushroom mons with Poké Ball designs on their caps - are these in Pokémon Black and White, as Voltorb and Electrode aren't native to the region. The worst part, their Ability (Effect Spore, a carryover from Gen III) can give negative status effects to any enemy who hits them! Their 'Dex entry suggests they evolved their cap design in an attempt to fool their prey; this is less likely to fool the Pokemon than it is to fool the trainer. At least they're slow, unlike Voltorb and Electrode, so if you want you can run away. Unless you want stick around to catch or defeat one they're not a huge deal.
 * Sudowoodo from Gen II pretends to be one of the trees that you're supposed to use Cut on. Instead, you have to water it because they're Rock-types. Used again in Emerald's Battle Frontier.
 * In Level 12 of Prince of Persia 2, there's a sword lying on the ground at one point, which you may think is a weapon upgrade, but when you approach it, it bursts into flames and attacks you. Run!
 * Ragnarok Online has a particularly bone-headed example; it has goddamned mimics. Of course Ragnarok has treasure chests. They're just usually part of the scenery. There are some proper ones too, though, albeit unusually rare for an RPG of any sort.
 * Ratchet & Clank Future: Tools of Destruction has these.
 * Rayman Origins features the Tricky Treasure Chest, it actually doesn't attack you nor it's hidden since the game has a special type of level just for it, instead when it sees Rayman & company, knowing what they're going to do at it, starts running away for its safety, making some frantically funny levels.
 * These things are horrible in Rogue Galaxy; the first few you meet a liable to cause a Total Party Kill. Not only are they about five times as strong as any random monster, but they surprise your party, leaving you unable to fight back for several seconds at the start of the fight! On the plus side, killing them always gives you a Hunter Coin. The lock on the box appears a little different from a normal area chest and the box stops opening partway just before the fight.
 * Rune Factory Frontier has the Monster Box (and it's higher-level cousin, the Gobble Box), the classic example of a treasure chest with sharp, pointy teeth. They're rather easy to pick out (you'll notice the lack of a command before you get close enough to set it off), aren't a threat save for their high defense, and, like all other monsters other than bosses, can be tamed to follow you around town and the dungeons and spit out free jewels and metals every three days.
 * An unusual case of of a monster disguised as a harmful item, the spike enemies in the Marble Garden Zone of Sonic 3 and Knuckles imitates the spikes you see in the level until you get near, after which they show themselves and start shooting. Interestingly, they're actually more useful, as their apparent spikes actually work like a spring. If it's possible for a nonsentient, mass-produced robot to have an F in evil...
 * A straight use from that same game is the boss of Flying Battery Zone Act 1, which looks like a normal animal capsule until you press the button on top of it, at which point it sprouts two spikeballs on chains and tries to kill you.
 * This trope is played straight is in Sonic and the Black Knight, which features actual chests that can come alive and attack you. However, the game plays a really mean trick when you first come across them, by placing one right in front of a load of fast-moving, spiked balls. Up until that moment, the player doesn't know about these chests, so upon coming across it, they'll just proceed to try and plough straight through it. Upon finding it's 'alive' (and losing almost all their rings in the process), the player has lost momentum and must then either jump or force their way clumsily through the balls as best they can, and promptly get knocked out because of losing most of their rings. It really is a case of Trial and Error Gameplay.
 * The Mimic Boxes from Seiken Densetsu.
 * Shining the Holy Ark has a particularly nasty example in the form of a Chest Ghost that possessed Soul Steal, likely killing Basso (your party's tank) until you could resurrect him in a church. Not pleasant when you need his attacking prowess for the area's boss.
 * In Spelunky, pots may sometimes contain snakes or spiders.
 * Treasure chests may sometimes contain a bomb. Very annoying if you're carrying a damsel.
 * Pandorites in Super Mario RPG are so brutal they're practically minibosses. They have high attack, defense, magic attack, can sometimes heal or summon, and are immune to just about all spells except for Mario's jump.
 * Super Paper Mario had Zombie Shrooms, which resemble normal restorative items, but come to life and attack the player after a brief delay.
 * In Super Mario 64, that Piano in Big Boo's Haunt can give the unsuspecting player a heart attack, as it suddenly becomes extremely loud when it wakes up.
 * In Super Mario Bros 2 / Yume Kojo: Doki Doki Panic, the end of level gate in world 7-2 attacks you. Once you defeat it, it acts like a normal end of level gate.
 * In certain levels of Super Mario Bros 3 there are some mini-Goombas that hide underneath and look like normal blocks, until you get close, when they spring up and jump at you. In the NES version you can tell these blocks from the normal ones because they don't "shine". In All-Stars, however, they are indistinguishable until you get close.
 * Super Mario World 2: Yoshi's Island has both fake flowers and fake One Ups.
 * The Tales Series. Justified somewhat by the fact that they give you All Divides, which are one of the games' most powerful items.
 * Fakes in Tales of Eternia get special mention. They take something like 10 times lessened damage from every attack you can make, including those with fixed damage like Distortion. They also start the battle Poisoned and lose a significant slice of their HP every few seconds. This makes every Fake battle more like a Hold the Line fight. (Distortion actually is helpful against Fakes, for a different reason - it holds the Fake immobile for several seconds while still allowing it to take Poison damage.)
 * Tales of Symphonia Dawn of the New World has a normal monster in the shape of a treasure chest
 * In the Notre Dame level of Timesplitters 2, there are several enemy changelings chained to the wall, disguised as the maidens that you're supposed to rescue. They can be told apart from maidens by closely inspecting their faces, and by the fact that zombies attack maidens, but not changelings.
 * Toejam and Earl has mailboxes you can use to purchase gift items. It also has really fast, really tough "mailbox monsters" that disguise themselves as ordinary mailboxes. It's possible, but somewhat difficult, to distinguish between the two by close observation: the eyes of a disguised mailbox monster may appear briefly if you remain idle.
 * Torchlight has the archtypical Mimics, but when they die they tend to drop much better loot than the usual not-trying-to-kill-you treasure chest.
 * Ultima V, although you can tell there's a chest monster around if the victory music doesn't play after defeating the monsters.
 * A few Ultimas had mimics, but the Ultima IX mimic actually had the body of a chest, on scaly ostrich legs. Tougher than most monsters in the same dungeons, but the rewards for beating them were usually better than what you could find in standard chests.
 * Ultima III had killer floors in Exodus' castle, which looked exactly the same as the regular floor, and so couldn't be distinguished from the background either before or after they engaged you in combat. They fortunately weren't very strong, and could easily be defeated after you'd already killed one batch of them, by standing on the treasure chest the defeated floors left. All Ultima III combat when you're standing on a treasure chest, regardless of what's meant to be under the chest, has the standard "woodland" map. Against which things that look like castle floor are somewhat conspicuous.
 * Vagrant Story puts an interesting twist on the Mimic: In this game, it's actually a giant hermit crab-like creature that uses an actual chest as its shell.
 * Vandal Hearts has Chest Monsters as well, also called mimics. In the game, a tactical RPG, chests are opened by striking them; naturally mimics are awakened in the same manner. They are indistinguishable from the normal chests until awakened. One Bonus Dungeon map takes this to the logical extreme, with a map filled with chests, only one of which is real.
 * Wario Land The Shake Dimension has man eating treasure chests in one of the Big Boo's Haunt type levels, which act like the man eating plants found earlier in the game. Strangely though, these treasure chests actually do contain the items needed in the level, and have to blasted open with a bomb to get the (real) treasure.
 * Wario: Master of Disguise also has Chest Monsters.
 * In addition to having mimics of varying strength scattered throughout, the Wild Arms games have a recurring Chest Monster superboss called the Black Box that you can only fight after opening every other chest in the game.
 * Wolfenstein 3d had a variation on this concept with some of the exit elevators. You may be given more than one door to choose, and if you pick the "wrong" one, then you find an elevator filled with guards, usually of the most difficult variety. Sometimes, the phony elevator may contain a secret wall that reveals rewards for your effort.
 * One level of Doom also has a false exit.
 * Wonder Boy and Adventure Island featured a grim reaper or eggplant monster hidden in some of the eggs, which clung onto you and drained your vitality. At least it doesn't turn you into an eggplant like in Kid Icarus. In Wonder boy the eggs containing this were spotted, while in Adventure Island there was no way of telling them of apart.
 * Some Roguelike games take that to similar extremes, and feature monsters that look like empty space. One especially Interface Screw-y creature is found in Zangband, making itself hard to identify, not only by being invisible, not only by looking like a floor tile even if you can see invisible monsters, but by having the name "It," so that all of its attacks will look exactly like those of a monster you can't see ("It touches you").
 * Even worse, It's Monster Chatter, screwing with the player even more.
 * In the Bonk series, some of the Florets contain "Venus Bonk Traps". You can tell a fake one from the real ones because they don't breathe.
 * Luigis Mansion, as well as fake doors and ghosts attacking from various hiding places, has Jarvis, who's quite literally a jar monster. Approach the jar looking for treasure, cue mini game and mini boss battle.
 * Subverted in Mystic Ark, in which not only are most mimics friendly, but they'll apologize when mistaken for a chest.
 * Dungeon Keeper 2 has a trap called the jack-in-the-box. Disguised as a magical item, your imps will try to take it to your dungeon, when it explodes.
 * At least in Wild Arms 3 and Wild Arms 4 the mimics were indistinguishable from regular boxes giving you some unexpected encounters. The payoff was decent enough to make it worthwhile.
 * Some chests in Casper: A Haunting 3D Challenge have Fatso hiding in them. You have to be ready to quickly get out of the way to avoid harm.
 * There are also fake vents Stinky hides in, waiting to give you a "Smell-o-gram!" These vents disappear along with him.
 * In the basement, Stretch's arm will reach out as you go past certain places. Usually where there's an item to pick up.
 * He's the hardest one to avoid, as well as the scariest, given the atmosphere.
 * Beyond Oasis features these. They're fortunately easy to detect due to them loudly snapping their mouths all the time.
 * Silver has animated chests that spring arms and legs (and swords) when you try to open them and attack you.
 * Dragon Age Origins has a couple of these in the ruined temple during the Urn of Sacred Ashes quest. Glass phylacteries may also count, if the player has never encountered one before.
 * Forever Kingdom has two different variants. One sort where a monster comes out of the chest and tries to attach itself to you, causing some sort of status ailment, and another where after opening, the chest will explode, which not only damages the player, but also causes him (or her) to drop all the money that they had been carrying.
 * The second and third games of the World of Mana series can have the randomly dropped treasure chests from monsters turn out to be one of these. In both games, they have extremely high attack power compared to normal monsters, but are less dangerous in the former, due to only showing up later on, and can be disabled through use of the Analyzer spell. In the third game, they can potentially appear at any point in the game, and have a stronger variant that starts showing up later.
 * Legend of Mana has the Polter Box, which looks like one of the game's treasure chests with spikes, eyes, and feet. They do live up to the treasure chest disguise, though, since they tend to drop rare and valuable crystals used for tempering your armor and weapons at the forge.
 * It's also possible to get a Polter Box as a pet, and bringing him along increases your chances of getting rare items from monsters.
 * Some of the secret bunkers in the NES port of Commando contain death traps such as snake pits or gas chambers.
 * Shooting certain walls in Legendary Wings's Lucky Stages generates enemies.
 * The final dungeon of Contact for the DS contains chest monster that sprout limbs, pull out a sword from inside of them, and then proceed to inflict beatings.
 * Early in Dubloon, you get to a room where to get the key, you have to open 5 treasure chests in correct order. Opening in wrong order results in a battle with a skeleton. Also, is a literal Chest Monster.
 * ? blocks in Alex Kidd in Miracle World will sometimes summon the Grim Reaper, who is an Invincible Minor Minion and hard to evade.
 * The Breath of Fire series has a Chest Monster as a recurring enemy named "Mimic", which is a living, breathing Mook chest. In a more straight example, the first two games has actual trap chests with a variety of effects (poison, damage or even reduce HP to 1) who are inflicted on whoever is at the head of the team.
 * Children of Mana has exploding chest monsters.
 * Delve Deeper has Lumber Mimics, which disguise themselves as treasure chests and then attack when your dwarfs try to pick them up. They have relatively low HP, but high attack power.
 * Neverwinter Nights: Hordes of the Underdark has an odd example. Instead of attacking you, it steals all your gear. You have to destroy it to get your stuff back, and it's immune to all your attacks. It's basically a harmless but annoying Puzzle Boss.
 * The Fatal Frame series had items that could be picked up marked by a glimmering point of light. During the first three games, they turn out to be very helpful in finding useful items that would otherwise be hidden in the dark environment. And then in the fourth game for the Wii, Tecmo pulls one of these where a ghostly hand would grab the character's wrist and require the player to shake the Wiimote to get loose.
 * Some "mystery" balls in Bug! will contain enemies or hazards instead of Power Ups.
 * Parasite Eve had chest monsters only in the Bonus Dungeon, the Chrysler Building. They didn't appear in the boxes until around the 30th floor or so and once found, you couldn't escape. Unless your armor had super high defense, you may not survive the encounter.
 * The King of Dragons has teethed monstrous chests posing as normal ones, awaiting to jump at you when in close proximity. Fortunately, they aren't really hard to deal with.
 * Magic Sword has several trap chests scattered on the stages, which either explodes in a wave of fire pillars, releases a group of monsters or summons a shower of rocks upon you; all of which do considerable damage.
 * Played literally in the Borderlands DLC Dr. Ned's Zombie Island with the Loot Goon, a Tankenstein with a red gun chest on his back. Killing him let you loot the chest. In a more straight example, in The Secret Armory of General Knoxx several lootable things (weapons chests, dumpsters, etc) had midgets hidden away inside them.
 * ADOM has traditional mimics. They don't look like chests because you don't generally find stuff in chests, just lying around; so they look like stuff lying around, ie. items on the floor. There are a few ways to recognise one. They used to appear on the map even if you hadn't explored that area again to find them, unlike real items, but that was fixed. They also appear as a random type of item symbol in a random colour, so they often seem quite colourful -- most armour and weapons is light grey for metallic, though special attributes on items have made the variety of real items more colourful as well. Finally, even when they don't appear on the map where you can't see them, they appear seemingly out of nowhere when in an area you've already explored; that's not impossible for an item, something could have dropped it there while you were away, but it is unlikely. The best place for them to hide is among the wide variety of stuff in a shop.
 * Played with by the "Trashure" enemy from Mario & Luigi: Bowser's Inside Story. The enemy looks like a treasure chest on the overworld. However, the player is not fooled because 1. it has eyes and moves around 2. treasure in this game comes in blocks, not chests. It's a great enemy to fight as it opens up at low health and Bowser can use his vacuum to suck in a lot of money. However, it tends to run away often.
 * Minecraft's popular Aether Mod introduces Mimics to the game, chests in boss dungeons - mixed with "normal", loot-filled chests - coming to life and attempting to bite the player when opening is attempted.
 * Magicka has chest monsters in the Challenge mode, though their disguise is a bit illogical since the game has no real treasure chests. Like most things in the game, they were only added as a referential joke.
 * Dark Souls has them and if you try and open them, they'll devour you instantly. What's worse, they're hiding 6-foot arms and legs inside their chest-shaped "head," and if you attack them they'll unfold their bodies and try to beat you to death, softly giggling all the while.
 * In Terraria, Mimics will show up in worlds once "hard mode" is unlocked. They're fairly tough, but drop loads of money and (possibly) a rare item when defeated.
 * In Psycho Fox, eggs may contain enemies instead of useful items.
 * Baldur's Gate has a single mimic in the entire series. It showed up in the sequel with confusing attacks.
 * Kid Icarus Uprising has Mimicuties, Underworld mooks disguised as treasure chests that sprout legs and start kicking you when you try to open them. They hit incredibly hard, move very quickly, and take more hits to defeat than nearly any other enemy in the game, making them extremely troublesome to deal with.
 * Stage 5 of the PC Engine shoot 'em up Rayxanber III begins with a bunch of powerups flying towards the player. They turn into monsters when approached.
 * Athena has annoying and hard-to-kill flying heads hidden in certain blocks.
 * Some boxes in Resident Evil 4 contain snakes instead of items.

Web Comics

 * Like every other RPG trope, the webcomic Adventurers! makes fun of this, this time by having the monster be bigger than the box it was hiding in.
 * Rusty and Co follows the adventures of a party of monsters, one of whom is a Chest Monster.
 * They fight one in Our Little Adventure. The way it acts, the color of the speech bubbles and its general appearance suggests it's a minion of The Lady of Fate and Fortune.

Western Animation

 * One appears in the Adventure Time episode "Dungeon", vomiting treasure when awakened.