Bloodworm

A Bloodworm. They attack you like a silverfish or mite, but they actively heal every time they attack. Bloodworms poison you, though. They could drop an item that could be used to make a potion of leeching or an enchantment that lets you steal the life of other things. Or they could not drop anything. They could drop themselves, which can be used in the offhand while fishing to catch fish quicker. They're scared of axolotls. I also propose that they're repelled slightly by firefly bushes, unless aggroed on that specific player. I'd prefer if they move in a slinky manner rather than a slithery manner like the other two mites. Bloodworms have a small chance of spawning when mining mud, similar to using an Ender Pearl, which can spawn a mite, and can infest mud things, like a silverfish infesting stone, with more having a chance to pop out of wet mud if you don't kill them in one hit. Bloodworm doesn't have to be the final name if the "no real animals" rule applies here.