The pearly grub has but one aim, to lay eggs in the mouth of a living creature. It is translucent with a hint of opalescence. It is the size of a cat and can crawl up walls and swim. Attempts to harm it in any way inflict the damage on the wielder instead.
Ok, another draft monster I haven't tried in play. I'm thinking if you touch the clammy thing and then hurt yourself, it will inflict wounds on it. Or, players can just try to avoid them, but they'll be crawling after the party throughout the dungeon. Oh, and if it lays eggs in your mouth . . . do you have to ask? That's bad.