GALVESTON, Texas — Just in time for Halloween, here’s something truly terrifying.

An Atlantic Croaker fish has been spotted at Galveston Island State Park with a a parasite in it called a tongue-eating louse. This parasite detaches the fish’s actual tongue, attaches itself inside the fish’s mouth and become its tongue.

The parasite does not kill the fish or harm humans. Instead, it just feeds on the fish’s mucus.

The tongue-eating louse is the only known case of a parasite that functionally replaces a host’s organs.