Alright, so take your basic (not DnD or any other universe specific) mimic: an unassuming treasure chest that turns out to secretly be a monster as soon as you open it. This particular creature is one that happens (for whatever reason) to look and feel nearly-identical to a chest, rather than being some sort of slime-thing that's using a chest as a shell.

How does such a creature move around, assuming it can't just use the easy method of shapeshifting itself some legs when needed? My current ideas involve it having some sort of (likely insectoid) legs it can fold up under itself while at rest (in a slight indention underneath to accommodate them), or that it has a softer, muscular foot on the bottom like a snail, only lacking the mucus. (Or it has less mucus, at least. Snails don't seem to NEED it to travel, though it helps with climbing.)

I'm assuming with the snail-like configuration it would be very slow, though that wouldn't really be a huge issue for an ambush predator. The legs would be faster, I think, but harder to hide.

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    $\begingroup$ Can you explain better why the normal legs underneath don't work for you? $\endgroup$
    – Andrey
    Sep 10, 2018 at 19:49
  • $\begingroup$ No particular reason, and it doesn't really matter too much to me, I just like the idea of it looking as much like a chest as possible from the outside. $\endgroup$
    – Thirteen
    Sep 10, 2018 at 20:15
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    $\begingroup$ You don't need external legs to move, check this robot out youtube.com/watch?v=n_6p-1J551Y $\endgroup$
    – csiz
    Sep 10, 2018 at 21:27
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    $\begingroup$ Have you had a look at the dark soul style mimics? They have long legs that can fold underneath the base of the chest. So it looks like a chest until they stand up. $\endgroup$
    – Shadowzee
    Sep 11, 2018 at 6:52
  • $\begingroup$ "And now for something completely different"... but you said "not DnD or any other universe specific". I currently play Prey and they have a science fiction version: Crab-like creatures that only use mimicking for hiding, but do all their moving and attacking in their original form. $\endgroup$
    – R. Schmitz
    Sep 11, 2018 at 9:50

10 Answers 10


Let's have fun with this....

  • It's a plant. It doesn't move, but like a Venus Flytrap it gets a portion of its nutrients by sucking the life out of people. Roots are for basic nutrients and water, and evolution played a nasty trick on Humanity by encouraging the plant to look just like a treasure chest with gold in it. Think Audrey II from Little Shop of Horrors.

  • It's actually a slug. Yeah, it looks like a treasure chest, but you can see the trail of slime it leaves as it moves around. What you think is a handle on the side is actually its nose evolved to help protect its eyes, which are just below the "handle." It's not actually after your blood, it wants your calcium.

  • It's not a treasure chest, it's luggage. Courtesy discworldemporium.com, we have a chest with teeth and a LOT of feet:

When it wants to lurk, it simply sits down. The feet are hidden inside the "chest."

  • Finally, for your consideration, my invention of "McHardy's Jumping Mimic," discovered by Francois McHardy (born to a French mother and Scottish father), this wonderful creature has a central protrusion beneath it that, when excited or really, really determined, allows it to spring from one place to another. Like cats landing on their feet and toast always landing butter-side down, their academians really don't know why1 it always lands correct-side-up, but with the exception of the case when prey is nearby, it always seems to.

1We, of course, are much more enlightened, having postulated the Felix-Bouturon Infinite Energy Generator and proven to ourselves the true reason why cats land on their feet and buttered bread lands butter-side down. It's a religious thing. Praise Glarnak!

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    $\begingroup$ Oh, you ninjaed me on Luggage references! $\endgroup$ Sep 10, 2018 at 20:14
  • $\begingroup$ @JBH Here is a higher quality, official Felix-Bouturon Infinite Energy Generator video. $\endgroup$
    – Stefnotch
    Sep 11, 2018 at 16:41
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    $\begingroup$ @Stefnotch, Cheers! Thanks for the improved link! $\endgroup$
    – JBH
    Sep 11, 2018 at 16:43
  • $\begingroup$ Sapient pearwood for the win! $\endgroup$
    – Mr Lister
    Sep 11, 2018 at 17:39

It has a heavy mass inside of its body which it can twitch/move vigorously.

It would be somewhat analogous to a mexican jumping bean: https://en.wikipedia.org/wiki/Mexican_jumping_bean

These are seed pods that have been inhabited by the larva of a small moth (Cydia deshaisiana) and are native to Mexico. The "bean" is usually tan to brown in color. It "jumps" when heated because the larva spasms in an attempt to roll the seed to a cooler environment to avoid dehydration and consequent death.

The mimic could contain a mass which it could similarly "spasm", thus throwing itself around with its own inertia. (It would move in any direction in a series of hops, provided it has traction on the floor. By twisting the mass concurrently with a hop, it would be able to adjust the direction it is facing. On the other hand, I doubt it would have much luck with stairs.)

Edit / final note: Based on the depictions of mimics I've commonly seen, perhaps its tongue could perform this function?

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    $\begingroup$ This is a hilariously amusing idea I hadn't considered. Just mimics bouncing noisily around dungeons and caves when they feel like moving. $\endgroup$
    – Thirteen
    Sep 10, 2018 at 20:16
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    $\begingroup$ Everything in D&D should move like this. You could roll some dice to see what direction a thing would go. $\endgroup$
    – Willk
    Sep 10, 2018 at 20:34
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    $\begingroup$ Given that it's contained in a box and somewhat menacing, I'm envisioning one of the semi-mythical "walking" hard drives, from the days when they were 500-lb monsters in their own enclosures. The movement there was driven by the spinning platter and head of the disk itself, and basically consisted of pivoting an inch or two around one corner, then the other, back and forth. $\endgroup$
    – Cadence
    Sep 10, 2018 at 21:54
  • $\begingroup$ Lots of video game monsters bounce around like this, so seeing or reading a description of this should be acceptable even if you don't explain exactly how they ambulate. $\endgroup$ Sep 10, 2018 at 22:03
  • $\begingroup$ This is the design used in many RPG video games, like the Dragon Quest series. youtube.com/watch?v=2k_Xu9pFt0s $\endgroup$ Sep 11, 2018 at 17:34

The D&D version is described in great detail in Ed Greenwood's classic Dragon article "The Ecology of the Mimic", and, as with the article as a whole, the mimic's locomotion is a brilliant balance of ridiculously silly and seriously plausible.

I don't have access to the magazine,1 but from memory:

Mimics are amorphous beings. They don't spend all day looking like a chest; they see or hear adventurers coming, and mimic a chest because they're smart enough to know that's how you catch adventurers.2 But they're not "some sort of slime-thing that's using a chest as a shell", they actually form their hides into rectangular shapes that look and feel as tough as wood, metal, or stone.3

They can rapidly form and extend pseudopods. Hence the famous Monster Manual drawing:


They can also secrete and dissolve a strong adhesive at will.

The way they move is by throwing out a pseudopod, covering it with glue, dragging their body over, and dissolving the glue as they toss out another pseudopod for the next "step". They can move about as fast as humans this way. This also means they can travel on walls and ceilings as easily as on floors.3

Also, most people forget that D&D mimics are intelligent, and will usually try to con the players through fast-talking instead of attacking them. And, while this is probably even less relevant here, they're immune to alcohol but have been known to feign drunkenness to trick adventurers.

So, how's that for an image: a mimic drunkenly dragging itself around the floor and the walls pseudo-fist by pseudo-fist, trying to make a deal with the PCs.

1. It really is worth reading, but I don't know where to find it. I mean, I'm sure you can find a pirated copy somewhere online pretty easily, but I don't want to encourage that. Go to the library, maybe?

2. They mimic other things in other environments. A statue in a city so they can eat people tossing coins in the wishing well, a bundle of war pennants in an orc camp, etc.

3. And how do they decorate themselves to have the right color and texture? I don't remember the details, but there were details. Something to do with pigment sacs and a special circulatory system, and also multiple rapidly growing layers of skin.

4. Yeah, that last part doesn't make sense—it should be harder to pull yourself up than sideways—but then AD&D never really got gravity.

  • $\begingroup$ I know a touch about DnD mimics, which is why I mentioned they weren't DnD specific, since I knew they could morph themselves and were intelligent enough to theoretically talk themselves into get moved by someone else if they wanted. But it's still really cool! I didn't know about that article, it didn't come up in my (very brief) googling (or I missed it). And the idea of fake-drunk mimics is absolutely hilarious. $\endgroup$
    – Thirteen
    Sep 12, 2018 at 20:05

How about it's a hermit crab-type deal? Crabs legs and mouth pieces are pretty uncomfortable to look at, probably because there are so many bits moving around. If it's ambushing people who try to open it up then it makes sense for it to have a good reach and fast hands, like a boxer crab. I really don't like crabs.

If it has big claws that reach out to grab whoever opens it up, it would have to fling the lid of the chest back really fast to counteract the momentum of it reaching forward, right?

To move itself around its legs would have to be close to the opening on the chest too and this thing would tip the chest on its longest axis to scuttle from side to side. Tipping would be difficult if it has stumpy limbs, so these appendages would have to be long and/or chunky.

Being geared up to scuttling side to side is practical if you're a chest because that'd be pushed up against a wall unless it's a feature chest or the interior designers don't use the space in the room efficiently.

That wouldn't make this thing great at chasing but it's an ambush predator anyway. Unless you're in a dead end of a corridor.

As far as the chest goes, that'd just be whatever's around, evolving a shell that looks exactly like a chest is a long shot, especially if chest-fashion in this world shifts regularly like it does in this one. It'd take a lot of very specific genetic changes to form a shell that looks just like a chest and there would be a lot of really messed up looking chests that weren't 100% right if this were how the chests are being formed.

These things might be laying a whole bunch of eggs so the smaller ones might be catching small animals from like empty cans or cat flaps or whatever. Any hole they can get into I suppose. You seen the movie teeth? All viable options.

I guess these things would have to lie in wait for really long periods in the abandoned buildings to avoid being fumigated or something. They'd have to be really energy efficient to survive, or fed by whoever's using these things as a security measure.

Maybe to stay tight in their chest, vase or whatever they're wearing, this things should be secreting an adhesive from its abdomen/tail. It's probably worth noting that out of a shell, hermit crabs look a bit like a creepy hand.

What's the story about?

  • $\begingroup$ No particular story, I just ended up looking up mimics and I got to thinking about their biology (movement in particular, obviously), and was sad that I couldn't find a whole lot about it. I do like the hermit crab idea (what can I say, I have a soft spot for hermit crabs, they're precious) and it's the easiest way to make a mimic-type creature work in my opinion, short of using magic as an explanation. Something that happens to use chests (or whatever is handy) as a "shell" is the most logical explanation for a mimic! $\endgroup$
    – Thirteen
    Sep 12, 2018 at 20:01

The mimic can transform itself into something that someone else will move to the desired location

A crate mimic might always be stuck as some variety of crate, but it can still switch up its label. Mimic wants to go to the big city? Add a mailing address. Mimic wants to lay low for awhile? "Industrial Waste - Do NOT Open" and boom, you're in the local swamp.

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    $\begingroup$ Really liking this idea. Seems like something useful in much more broad case then just this question. $\endgroup$
    – Cerberus
    Sep 11, 2018 at 5:33

It has legs, but not connected to any externally visible hips.

It can fold its legs beneath itself, so that in a sitting position the legs are completely hidden by its four sides. Just like a sitting chicken.

It also had many, many legs that move in a centipede-like motion. Meaning it can run surprisingly fast for its shape and size.

Luggage deserves some love

It will also follow its master wherever they go, even in time and into the outer dimensions. And you absolutely don't want to see these things mating.


My suggestion is similar to abarnert's, and I suspect it might be influenced by having read Ed Greenwood's article at some point in the past. But it's got it's own little twist to it: instead of using a sticky pseudopod to move around, what if the sticky part was its tongue? So when closed, looks like a normal treasure chest. When it wants to move, it opens the lid, and the hidden, sticky tongue pops out. Like a frog or reptile, the tongue is very stretchy, and the inner mimic is mostly just tongue. It would shoot its tongue at a location a few feet away, anchor itself with, perhaps, special barbs designed for this purpose, and then drag itself forward. Detach tongue, repeat. The other use for this stretchy, sticky, barbed tongue would, of course, be ensnaring prey that wandered too close.

Ooh, or instead of pulling with the tongue, it could push! Then it would look rather like a clam "walking" around.

  • $\begingroup$ I don't know who came up with the idea of a stick mimic tongue instead of sticky mimic pseudopods, but it's definitely been used many times before (possibly originally under the influence of the Luggage)? But I don't remember anyone ever using it for locomotion, and that is a truly great image. (The only real problem is, how could you even tell it was pretending to be drunk when it's already flinging itself around the room by tongue?) $\endgroup$
    – abarnert
    Sep 11, 2018 at 19:59

I like the idea of a chest-like monster which hides its arms/legs inside itself.

When he feels like moving, he just needs to put them outside its "mouth"; the idea would be for it to look and move like a spider in this "walk/run instance".

This also gives it the ability to actually grab its preys once they are close enough.


I know you've accepted an answer, but I might as well give some of my thoughts too.

It's sessile: be it an animal or a plant, it needn't move at all. It could root itself to the ground and simply wait for a passer-by. When the human - or some other curious animal - touched its exterior (Which could be covered in mechanosensory trigger-hairs), its jaws would open and snap shut, severing the person's arm and digesting his or her hand.

It's a gastropod: or, at least, it moves like a gastropod. On its underside, there is a muscular ventral foot - not like ours, but like a slug or snail's. The foot would be lubricated with mucus and covered in cilia (tiny hair-like organs), and the Mimic would move by way of waves of muscular contractions of the foot.

It's a slime mould: again, I'm not suggesting that you place Mimics taxonomically as pseudo-multicellular microbes, but at least that they move like a colony of one. Basically, slime moulds move by swinging their gelatinous mass back and forth slightly, and then extending tendrils, pulling them across the ground. This movement would be very slow and hard to observe.

It's an echinoderm: Echinoderms, such as starfish and urchins, have ventra which are covered in tiny, hydraulic tendrils called "tube feet". They are, essentially, used like we would use our feet, except that they are so small that they can barely be seen without looking closely.

It's a ricochetal saltatore: well that's a mouthful. Basically, it would have a single leg (Stored inside the "chest" when not necessary), and hop like an Eponan Springcroc. Kangaroos released stored energy with each jump, which helps them jump further.


Mimics could be large fossorial creatures, such as giant earthworms, that dig burrows underneath chests, so that when someone comes near the chest, they can extend out and attack.


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