Oh dear God. Prepare to be horrified. The image you are about to see depicts the symbiotic relationship between weaver fish and isopods, a “rare parasite which burrows into host fish before eating and replacing their tongues with itself.” Despite eating it’s tongue and helping itself to whatever the fish is eating the isopod doesn’t harm the host fish. In return the fish gets to look like an alien badass:
[via Discover Online]