Monster: A Naturalist Mimic - The Carcass Crab

The Carcass Crab

HD: choose or roll
     1: Squirrel, ermine, etc. Dmg: 1x1d2, 2x1d2
     2: Fox, wildcat, etc. Dmg: 1x1d4, 2x1d2
     3: Wolf, badger, etc. Dmg: 1x1d6, 2x1d2
     4: Goat, boar, etc. Dmg: 1x1d8, 2x1d4
     5: Deer, horse, etc. Dmg: 1x1d10, 2x1d4
     6: Bear, etc. Dmg: 1x1d12, 2x1d4
     7+: More formidable monsters Dmg: 1x1d12, 2x1d6
AC: As Plate (thick chitin)
Attacks:
     1xBite (damage as above) & if 5HD+ decapitate on crit if Gripped
     2xClaw (damage as above), and Grip
MV: 30' sideways scuttle (can only attack with 1 claw unless it moves 20' or less)
NA: 1
Treasure: HDx10x1d10 gp "pearl"

The Carcass Crab has elbowed its way into a very particular evolutionary niche. Most often found in areas of lush wildlife, each resembles a dead animal (usually a mammal), lying on its side, head missing, chest rent open, ribs protruding. The chest is in fact its wide maw; the ribs sharp teeth, jaw hinges capable of opening up to 120 degrees. The legs jutting out from either side are cleverly camouflaged clawed arms, used to grip victims if they narrowly escape the initial snap of the maw. It's real, multiple crustacean legs remain tucked under it, out of sight.

Completing the effect is the very real blood and viscera of its most recent kill, flies buzzing. The blood attracts further prospective victims: largely scavengers, but often curious predators. Even if it's too big to swallow whole, the crab will attempt to bite off its head (likely curious and sniffing near the mouth already), and consume the rest at its own pace. More agile escapees likely soon give up on piercing its hard shell.

Larger specimens may attract intelligent prey due to regurgitated weapons and armor, or its eyes, between rib-teeth, resembling shiny black orbs; perhaps the jeweled pommels of daggers, abandoned after the kill? A special gland, colloquially known as the Treasure Sack, accumulates smaller indigestible objects and material. As the crab grows, precious metals form pearl-like agglomerations, typically worth HDx10x1d10 gp.

The crab will molt multiple times during it's life as it grows fat on easy prey. Each phase resembles a slightly larger animal, maintaining verisimilitude. Its thick chitinous shell is detailed with fine ridges, mocking glossy fur, if a bit matted. Most phases appear headless, likely due to it being much easier to mimic asymmetrically than a full head.

Characters have a base 1-in-6 chance to notice something is wrong from outside of bite range.


Conceptual Status: Warning - Untested but Play-Ready

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Commentary
Mythic Underworld creatures are all well and good, but rarely can I resist considering how something resembling them could be plausibly evolved. The absurd degree of mimicry that real-world insects achieve almost makes me accept traditional mimics as-is, but having been exposed to enough biology (see the wonderful Endless Forms Most Beautiful for some truly mindblowing revelations about how life works that I, at least, didn't hear about in school), I fail my save to suspend disbelief.

I encourage you to comment below, rather than elsewhere.

Long live the Blogosphere!