The deeper levels of Castle Meatgrinder are populated by the slimiest critters in the dungeon. Oozes, slugs, and all sorts of wet nasties - you can't get slimier than actual slimes, after all. Naturally, these fellows are perfectly at home in the dank corners of the dungeon.
Rumor has it that these particular dungeon denizens have a particular hatred for moneylenders and female adventurers, but some say those are bedtimes stories designed to scare the gullible.
Whatever the truth about these particular monsters, they are very rare.