Inspired by
this, I've modded in 'arboreal octopuses'. They're cephalopods, roughly 3/4 the size of a grizzly bear, that have lungs and live in tropical rainforests (I figure that's how they keep themselves moist), capable of grabbing weapons and items with their tentacles similarly to giant desert scorpions. In addition, they're brightly colored and thus valuable as pets, and can serve as bodyguards because not only can they hold weapons, they're intelligent enough to gain skills through CAN_LEARN (which is somewhat realistic, since octopuses are capable of manipulating tools occasionally). Maybe I should give them CANOPENDOORS...
can octopuses open doors? I'll have to figure that out.
I embarked and had everyone try to wrestle one as a test. The octopus grabbed a pig tail fiber toga off one of the dwarves and began thrashing the others with it, caving in several skulls before getting punched in the brain. They're interesting in that respect, actually, because blunt weapons can hurt them even though they don't have bones; their brains can be bruised with a sharp blow to the body.
At one point, arena tests showed an arboreal octopus wrestling a sword and shield out of a knight's hands and dismembering him before biting through his skull. I'll have to see how they perform in combat when wielding weapons they've grabbed from enemies (outside the arena). Perhaps they belong in savage biomes