"I was looking for Flesh-eatin' Slug Repellant, - They're ruinin' the school cabbages."
Rubeus Hagrid ~ CS4
Apparently a frightening creature, since one student was scared enough of them to have their Boggart turn into one (PA7).
Hagrid once needed a repellent for Flesh-Eating Slugs that were getting into the cabbages, and went shopping for it in Knockturn Alley, as they were apparently unavailable in Diagon Alley.(CS4).
There really is a flesh-eating slug in the muggle world. It eats worms with its razor sharp teeth.
It's unclear why flesh-eating slugs would cause a problem for cabbages, unless they also eat plants.