Homebrew Box Mimic Species Details

Description
Mimics are known for being sneaky, hiding in plain sight often enough that even novices know to look out for them. Rarely, do they possess much intelligence in the wild. Those that do possess intelligence, however, often outlast their more...dimwitted brethren, in public, urban areas. That being said, mimics tend to reach maturity at around ten years old, and tend to live for roughly a hundred or so. Mimics do not possess natural limbs, but they do have a fully-prehensile pseudopod capable of reaching roughly 2 meters at most.

Biology
Mimics, like most species of the changeling genus, have incredibly unstable biomass. Their bodies are protected under a faux-wood shell typically composed of a type of keratin or chitin. Some subspecies may have faux-metal bands around them - these were originally for wooing mates, but they now serve to enhance a mimic's disguise. The musculature of a mimic, beneath its shell, is very flexible, almost amorphous. Using partner bacteria and special enzymes, the muscle tissue can warp and reshape itself, stretching to fit a preset shape the mimic is familiar with. To become familiar with a shape, the mimic must consume the object or creature. Once familiar with a form, the muscle tissues can more accurately replicate fine details. Only partial transformations of muscle structures are possible. It is also important to note, that a mimic cannot transform the faux-wood shell surrounding them. Only the softer tissue of inside their "chest cavity", beneath the shell, and the mimic's underside may morph.

As mimics are able to morph their bodies and stretch their muscular tissue so much, they contain a lot of densely-packed biomass. So much so, that mimics need to eat a lot to keep up with it. While this ravenous extra-hunger doesn't exactly affect mimics health-wise, it does however impact passive regeneration abilities, which are directly influenced by the stockpiled biomass using itself up to replace missing or damaged cellular structures. If a piece of the mimic's muscle tissue is severed completely, the tissue dies, and any stored up biomass held within that tissue is lost. These muscle tissues tend to disintegrate upon being severed. A mimic may have multiple partial transformations active, but seeing as a mimic's base form only has a pseudopod as a single proto-limb, anything more than a single limb takes time and practice to master using.

Mimics do not have visible sensory organs. This is because they do not have traditional sensory organs. There is a magical sensory organ within the mimic that provides simple layouts for the mimic's awareness (akin to echolocation), outlining nearby shapes and alerting the mimic to nearby moving objects. At low levels, this awareness is easier to fool. This sensory organ detects only presences and sound.

A mimic's pseudopods are fully prehensile. They have about two meters of reach, and can be used to grapple. The jaws of a mimic are exceptionally large, but they do not have teeth in their entire jaws, nor an intestinal tract. Their mouths can secrete a mild acid to break down things stuck in their jaws. Most mimics have evolved to resemble chests. There are, however, groups that have split off from the main species and evolved to emulate other objects. Smarter mimics will carry their belongings within themselves as opposed to in a backpack, as they do not naturally possess shoulders from which to hang a backpack from.

Society and Culture
Mimics are rather renowned for their behaviour as ambush monsters. As such, they don't tend to be welcomed into many enlightened (typical player species) societies. Mimics do not tend to have societies of their own, at least none that have been observed by enlightened races. Those observed in the wild typically wind up living largely solitary lives. Those intelligent enough to develop complex enough communication skills sometimes wind up in an uneasy peace with enlightened societies. It is actually through a few of these enlightened mimics that we know of a bit of mimic psychology. Often, a mimic's hunger is not restrained by morals. They are not picky with their prey, because they typically lack the intellect to ponder such choices. As mimics do not exactly have anything resembling polite society, questions about the morality of things are difficult for them. They must learn the concepts of right and wrong as defined by whatever society they attempt to connect near. As such, a smart enough mimic to communicate would need to be taught that eating humans when living near a human village is bad. They do not instinctively know this. The naturally smarter mimics will tend to gravitate towards societies, and will tend to be curious.

Mimics are inherently selfish and greedy creatures. They may not necessarily have malicious intent, but they focus on a system of "I want it, so I get it". Doesn't matter if anyone else owns whatever else it is. Shiny objects are usually the subject of this desire. A few highly-intelligent (for their kind) mimics have been seen to develop a sense of respect for people beyond other mimics. Those respected are typically permitted to keep favoured objects, though this respect seems to require earning - even among other mimics, there seems to be no such thing as inherent trust or respect.

Historical Reference
Not very much has been considered noteworthy enough about mimics to note down. Thus, the only real references we have about them are about their more violent, self-centered actions. It is speculated that mimics may behave differently if bred and raised in captivity, to promote integration into polite society. Though, there is no written record of anyone actually going through with this.

Box Mimic Traits

Mimics require biomass for large disguises. Thankfully, this is easily obtained by consuming prey, even with its armour on.

Arcamollusca Fasciotesta

Your active traits are available as spells and cantrips for you to choose in lieu of a wizard's spells. They don't function like traditional magic - as a mimic, you're fighting using your inherent abilities as opposed to magical prowess.

Biomass Storage (passive - attached to my Rogue-Mimic sub-class feats):
Consuming prey allows you to store biomass, which you can condense and store within your muscles. You can stretch this out to warp your form into larger structures. Biomass is only ever lost if a piece of you is severed. At a high enough level, biomass can passively regenerate some of your health.

Iron Stomach (passive - attached to my Rogue-Mimic sub-class feats):
You cannot be poisoned, be it from venom or otherwise.

Changeling Dialogue (passive - attached to my Rogue-Mimic sub-class feats):
You may hear and converse with creatures who communicate with high frequencies. This includes other shapeshifters.

Density Purge (passive - attached to my Rogue-Mimic sub-class feats):
You can convert your stored biomass into added density and weight for as long as you concentrate. This is converted back once concentration ends.

Biomorph (active - attached to this species):
Given that you have enough biomass, you can morph your form to incorporate bodily functions of other creatures once you are familiar enough with them and their function. This will, of course, require you to eat them.

Unstable Biomass (active - attached to this species):
You can stow up to 1 cubic meter within yourself. Living beings will suffer radiation damage after long enough stowed within you and not eaten.

Metal Mimicry (active - attached to this species):
Once you are familiar enough with a given metal, you can actually restructure your fleshy pseudopods to resemble that metal.

Camouflaged Stance (active - attached to this species):
You can morph your fleshy body to resemble anything you're familiar with - this is perfect for ambushes, as long as you can hide your faux-wood shell.

Life Absorption (active - attached to this species):
During a rest, you may consume a corpse with both an intact heart and intact brain in order to maybe adapt one of their racial traits on top of your own. IE harvesting stonecunning from a dwarf corpse.

Sensory Core

The Sensory Core is the name of a magical organ within most extant species of the Changeling genus, granting an acute mental image of the species' surroundings, as a 360° view around the species. This sense, for mimics, is their only sense beyond taste and touch, unless they morph their body to create other sensory organs. This organ works in both light and dark, and allows the mimic to 'see' shapes and general outlines around it. Fine details and colours are not detected. This projected sensory field can be tricked by the presence of materials that absorb magic, preventing the information from reaching the mimic's core.

This organ allows rudimentary 'sight'. As such, mimics are, by nature, deaf and incapable of detecting scents, on their own. Touch, colourblind pseudo-sight, and taste are the only three senses natural to the mimic. If a mimic develops other sensory organs, this will very likely cause a sensory overload, and take a lot of time to adjust to.

As mentioned earlier, this sense can be fooled easily. Think of sensory hormones constantly being released into the air, and being reabsorbed back into the body. The ones that are reabsorbed and have changed slightly indicate the presence of something nearby. If they soak into anything that absorbs or cancels magic, this prevents the hormones from returning and providing sensory information.

This 'sight' does not cover a wide radius. At level 1, a mimic's 'vision' radius extends to about 10 feet around it at any given point in time. For every level increased, the radius grows 5 feet.