I read about a real life beetle that lives in icy regions. It is so adapted to the cold climate that holding it in your hand will kill it in seconds.
Doesn't matter much, but if its a beetle we could stick on Megahorn.
Fuck that! Make it a worm!
No! An assasin bug! That sort of makes sense, possibly flash freezes its sleeping foes? Stick some ability in about it being hard to hit, thus giving it rock immunity (SR).