Cymothoa exigua is a parasitic crustacean of the family Cymothoidae. It is the only parasite known to effectively replace a body organ, in this case the tongue. The Cymothoa Exigua enters a fish’s mouth and attaches itself to its tongue. Next it clamps down on the tongue to cut off the blood circulation and eventually part of the tongue just falls off. After that it replaces the tongue in every way by clamping on to the tongue’s remaining stump and the fish carries on oblivious to it’s aesthetically hideous tenant. Cymothoa Exigua actually compensates for the damage it does by becoming the fish’s tongue.