9 Extinct Exotic Sea Creatures

Frilled Shark
The frilled shark dates back roughly 80 million years and was thought to be extinct until two Australian fisherman accidentally caught one in 2015. Awashima Marine Park/Getty Images

File this one under "almost extinct." With a face that only a mother could love, the frilled shark (named for its six pairs of frill-like gills) is quite possibly the ugliest, strangest and most frightening monster on this list [sources: SETFIA, Chappell]. This bizarre and menacing creature is not, in other words, the type of shark one might find dancing behind Katy Perry during a Super Bowl halftime show.

The frilled shark kind of looks like an ugly version of an electric eel. Its 5-foot (1.5-meter) frame slithers around with the help of a few small fins and strikes a bowel movement-inducing fear in the heart of any human who crosses its path, with a set of 300 razor-sharp teeth laid out in 25 rows. The shark has been called a "living fossil" thanks to those primitive features and an origin that traces back roughly 80 million years [sources: SETFIA, Chappell].

Until recently, it may have been safe to believe that this beast had gone the way of the megalodon. That's until a couple of Australian fishermen happened to inadvertently scoop one up in their net in January 2015 [source: Chappell]. It's one of a few known modern encounters with the beast, at least by anyone who's lived to tell about it.