Hydra
Trapped in the dark and left to starve
Men huddle for warmth and devour one another
Bodies muddle where none can see
Heads are left upon the mass when bodies are chewed away.
Necks stretch to find more morsels
HD per number of heads
Makes 1 attack per turn per hit dice.
Attacks of 6+ sever heads. They seek the mass and reattach after 1 round healing the damage.