Meet Cymothoa exigua, a nasty little parasitic crustacean that has evolved a particularly ingenious way of making himself comfortable in his host. The parasite enters his host, the spotted rose snapper, through its gills, and proceeds to suck blood from the fish’s tongue until the organ atrophies and drops off. The clever little bastard then becomes the fish’s tongue, grabbing on to the stub of the original tongue and behaving just like the real thing. The parasite feeds off the fish’s blood and mucus, apparently without harming its host. Charming.