More than two decades after spotting a mysterious, gelatinous, bioluminescent creature swimming in the deep sea, California researchers this week announced that it was a new species of sea slug.

A "remarkable" new sea slug nicknamed the “mystery mollusk” has been discovered swimming deep in the ocean's "midnight" zone. The species has "unique" adaptations for life in the pitch-black depths including a large gelatinous hood to trap prey,

According to Bruce Robison, a senior scientist at the Monterey Bay Aquarium Research Institute, it’s “the most comprehensive description of a deep-sea animal ever made.” The team published its description in Deep-Sea Research Part I and comes on the heels of over 150 additional sightings of the creature by MBARI ROVs.

A “remarkable” new sea slug nicknamed the “mystery mollusc” has been discovered swimming deep in the ocean’s “midnight” zone. The species has “unique” adaptations for life in the pitch black depths including a large gelatinous hood to trap prey,

One of the weirdest sea slugs known to science has been discovered at a staggering depth, swimming around right down in the Midnight Zone between 1,013 to 4,009 meters (3,323 to 13,153 feet). As well as becoming the first sea slug known to live in the deep-water column,