You are looking at a parasite called Cymothoa Exigua. It enters through a fishes gills, eats their tongue and then replaces it. This lil delight literally sucks out the blood off the fish's tongue, and then replaces the withered tongue with itself. Now everytime the fish eats, it takes away a portion of the food for itself.
Hello Milan, I just watched your video on disassembling/reassembling the CZ 550. I have spent days looking for something like this. I now have no reservations taking apart my rifle. I like to do this with all my guns so I understand them "inside and out". Thank you very much for the information. It is greatly appreciated.