The Hagfish Is the Slimy Sea Creature of Your Nightmares

"At the bottom of the ocean dwells a bizzare-looking creature. A fish so ancient, it has remained unchanged for 300 million years. This is the hagfish."  
Ooooh, so excited. It's mini-documentary time big kids...

The hagfish is a slime-emitting ocean-dweller that's remained unchanged for 300 million years--and it shows. It has a skull (but no spine), velvet smooth skin, and a terrifying pit of a mouth that’s lined with rows of razor-sharp teeth.

Smithsonian Channel