Thingamajigs are creatures that you just don't know what they are. They're kinda.. watery, plasticy, fleshy, sometimes fury. They're completely random looking each one of them. They may have eyes for toes, or toes for ears, if you can even tell they're toes or ears or eyes. Some look intresting, some disturbing, some may even look compelling. but point remains: They're just thingamajigs.
Features:Thingamajigs have the following features, class abilities may override if more then given:
Roll 1d6. on a 1, creature has d4 hd. on a 2, d6; 3, d8; 4, d10; 5, d12; 6, d20.
Roll 1d4. on a 1, full attack progression; 2, 3/4ths attack progression; 3, 1/2 attack progression; 4, 1/4th attack progression.
Traits: Thingamajigs possess the following traits (unless otherwise noted in a creature’s entry):
Blindsight 30ft, Tremorsense 60ft
Immunity to poison, sleep effects, paralysis, stunning, disease, and mind-affecting spells and abilities (charms, compulsions, phantasms, patterns, and morale effects).
Not subject to nonlethal damage. Immune to damage to its physical ability scores (Strength, Dexterity, and Constitution), as well as to fatigue and exhaustion effects.
Immunity to any effect that requires a Fortitude save.
Not at risk of death from massive damage, and remains conscious until -9hp.
Compression. Thingamajigs can compress they're bodies into spaces four sizes smaller. they take a -2 penalty to all actions per size they're compressed.
Assume Skeletal Frame. Thingamajigs can eat the flesh off of a living creature, leaving only its bones, Then form around the bones to make itself appear that shape. It needs Disguise skill to appear that creature, but they still look obviously humanoid, or feline. Just.. without fur, or hair, if they do it still looks like the thingamajigs own fur/hair.
Thingamajigs with 8 or more hit dice can appear as a generic member of the species they assumed.
Thingamajigs with 17 hit dice can assume an exact likeness to the creature who's specific skeleton they assumed.
Quite frankly this looks more like a hybrid* of a subtype and inherited template for aberrations. Aberration fits the fluff perfectly. One thing I will say is that figuring out the CRs would be especially tricky since it varies each time.