A parasitic Crustacean in the same order as woodlice and pillbugs (or sowbugs and roly-polies), Cymothoa exigua is the only parasite that effectively replaces a body part of its host. As it drains blood from the tongue of a fish, the original tongue shrinks away while the fish manipulates the parasite as a new appendage. This amazing animal was even featured on the Colbert Report, though it was mistakenly referred to as a fish itself! Visit bogleech.com for more parasites, monsters and weirdness.