Ogrefish

A hunter with iron nail teeth
The ogrefish, Anoplogaster cornuta, is a large abyssal (deep water) hunter with tough, armored skin and 4 long, straight teeth that resemble iron nails. These teeth are so long that when the jaw is shut, the lower pair must slide into special sheathes on either side of the fish's brain to avoid impaling it.
Although food is scarce 5,000m under the sea, the ogrefish uses its long teeth to impale its prey, trapping them with rapid lunging movements.
Generation gap due to looks?
In this species, juveniles differ so strikingly from adults that it took 50 years for fish biologists to realize that they were same species.