This is some footage from the Monterey Bay Aquarium Research Institute (MBARI) of Bathydevius caudactylus, aka the mystery mollusc. It lives in the midnight zone (1000 – 4000m) of Monterey Bay, and is recognized as a swimming sea slug. But can it really be a slug if it can swim? I’d like to argue these should be classified as swugs.

“With a voluminous hooded structure at one end, a flat tail fringed with numerous finger-like projections at the other, and colorful internal organs in between, the team initially struggled to place this animal in a group. Because the animal also had a foot like a snail, they nicknamed this the “mystery mollusc.”

The swimming slug uses bioluminescence to confuse would-be predators and stay safe. And if there’s one thing I would want to be in the deep sea, it’s safe. Well, besides not in the deep sea at all. There’s nothing down there but fish with sewing needles for teeth and Ursula’s garden of shriveled merpeople souls anyways.