Grythok

A grythok is 2 to 6 inches long, a soft oval body hidden entirely under a tough, domed, leathery shell. Underneath are its sense organs, a round mouth ringed with sharp teeth, and twelve short, pointed legs that barely walk but sink like barbs into anything softer than leather, holding prey still while the mouth fastens. Released willingly, the barbs do no harm, but tearing a grythok loose costs the victim 1-4 hit points.

Grythok cling to cave walls, floors and ceilings. Any non-evil aura within 60 feet rouses one, and it takes wing in a feeding frenzy while emitting a shriek humanoids cannot hear. Other grythok within 60 feet answer this dinner bell at two per round, and each newcomer shrieks too, so the call ripples outward through tunnels.

It smells flesh, living or dead, and goes for exposed skin. One successful hit means both barbs and teeth are in; it then feeds in round bites, shifting to fresh skin without loosening its grip, until it has inflicted 30 hit points and drops off full. A successful attack roll plus a Dexterity check pulls one free, though the victim loses 1-4 hit points. Every tenth grythok carries disease from its filthy haunts; this is not magical and allows no saving throw.

Grythok die to ordinary attacks, but striking one on a person is hazardous: a hit deals the same damage to the victim, and a miss requires an attack roll against the victim.

These underground scavengers need filth and live almost only in sewers, latrines, cesspools and garbage pits. They eat almost anything but favor meat, such as rats, insects, worms and snakes, and would be handy waste disposals if they were not so quick to attack.

Long adaptation has made them immune to most diseases, which they carry and spread freely. They lay eggs twice a year, but numbers grow slowly because they often eat their own eggs by accident.