Barreleye Fish with Transparent Head

Over on National Geographic's YouTube channel, there's some very cool footage of a barreleye fish with a transparent head.  Scientist have been aware of its existence for nearly three quarters of a century but have only in recent years caught a glimpse of a live specimen and, remarkably, have caught it on film.  This creature conjures up some great ideas for others like it to terrorize player characters in an undersea tabletop roleplaying campaign setting.  Enjoy!