If this doesn't make you cringe..

Eww huh?

Well this little feller "Cymothoa exigua" that appears to look like something from the alien movies, is a parasitic louse that attaches itself onto the tounges of unsuspected host fish. This parasite enters the fish's mouth through the gills. Once attached, the parasite sucks the host's blood through the claws from it's three front pairs of legs. Thus, the poor fishies end up dying due to the lack of blood reaching their tounge, this happens as the louse begins to grow in the fish's mouth basically replacing the fish's tounge by attaching its own body tissue to the stub of the tounge.

Imagine being one of these fish having some foreign creature grow inside of you sucking the soul right out and you not being able to do a darn thing.

Just recently, this "tounge devouring parasite" was found inside a weaver fish off the Jersey coast. Don't worry this parasite won't affect humans, thank god. (Some of the info used is from wikipedia)