The Nefacossus, Nefacossus fluvius, is a strange, unique, armored, arthropod-like craniate from the wetlands and rivers of Skull Island. It measures 3 feet long.
A case of convergent evolution with the neopedes, Nefacossus is descended from primitive craniates, a clade from which lampreys, other vertebrates, and hagfish sprang. Instead of eyes, Nefacossus uses its rudimentary lateral line to home in on movement in the water that will betray the presence of small prey.