Researchers have discovered a new species of glowing sea slug deep in the ocean’s midnight zone.

Monterey Bay Aquarium Research Institute (MBARI) scientists said in a press release on Tuesday that while Bathydevius caudactylus is classified as a sea slug, it was nicknamed the "mystery mollusk" because the creature was unlike any other that’s been encountered before.  

The mystery mollusk’s genus name, Bathydevius, is a play on the deep-sea animal’s "devious" nature that fooled researchers, the researchers said.

Bathydevius is the first nudibranch, or sea slug, known to live in the deep sea. The sea slug’s body is made up of a large gelatinous hood and paddle-like tail. It can glow with bioluminescence. 

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It lives at an extreme depth of 1,000 to 4,000 meters, or 3,300 to 13,100 feet, below the surface in the ocean’s midnight zone, creating a unique challenge for scientists who’ve worked for decades to catalog the mysterious animal.

"We’ve invested more than 20 years in understanding the natural history of this fascinating species of nudibranch," said MBARI Senior Scientist Bruce Robison. "Our discovery is a new piece of the puzzle that can help better understand the largest habitat on Earth."

Researchers found that Bathydevius evolved to find unique ways to survive in its environment.

It uses a cavernous hood to trap crustaceans "like a Venus fly trap plant," like some jellies, anemones and tunicates. The mysterious creature also hides from predators in plain sight, taking advantage of its transparent body. 

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If it feels threatened, however, the sea slug will light up with bioluminescence to deter and distract hungry predators. Researchers once observed the creature illuminate and detach a "a steadily glowing finger-like projection from the tail, likely serving as a decoy to distract a potential predator."

Bathydevius, like other nudibranchs, is a hermaphrodite, having both male and female sex organs. Researchers said that the animal will descend to the seafloor to spawn, using their muscular foot to anchor to the muddy seafloor before releasing their eggs.

MBARI scientists said that it was only thanks to the facility’s advanced underwater technology that they were able to compile the most comprehensive description of any deep-sea creature to date.

"What is exciting to me about the mystery mollusk is that it exemplifies how much we are learning as we spend more time in the deep sea, particularly below 2,000 meters," said MBARI Senior Scientist Steven Haddock. "For there to be a relatively large, unique, and glowing animal that is in a previously unknown family really underscores the importance of using new technology to catalog this vast environment." 

Venomous creatures were spotted washing up on the beaches of the Outer Banks in North Carolina, and the National Park Service sent out a warning about the punch these slugs pack.

The Cape Hatteras National Seashore posted on Facebook that Blue Sea Dragons (Glaucus atlanticus) have been spotted on the beaches.

"This venomous sea slug lives in the open ocean and occasionally gets stranded on land following strong winds," officials from the National Seashore posted to Facebook. "They may only grow to about an inch long, but don't let their size fool you. They pack a punch!"

According to Oceana.org, Blue Sea Dragons go by other names like sea swallow or blue angel and can grow to about 1.3 inches.

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They are often found throughout the Atlantic, Pacific and Indian oceans in tropical and subtropical waters.

The specimen is considered a sea slug and spends most of its life floating upside-down at the surface and staying afloat by storing air bubbles in its stomach, the organization wrote.

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Cape Hatteras National Seashore officials say Blue Sea Dragons move through ocean currents feeding on their meal of choice: the Portuguese man o’ war.

"Because their meals consist of such a venomous creature, they are capable of storing that venom for their own defense," the park service wrote. "They concentrate that ingested venom and deliver a sting that is even more powerful! Talk about a fiery bite for such a small dragon."

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Since these tiny slugs carry such a strong toxin, park officials advise anyone who comes across one of these blue beauties to admire it from a safe distance and be cautious of others nearby.

"Blue Sea Dragons can travel in groups known as ‘Blue Fleets,’" the post read. "If they are discovered, dead or alive, they remain venomous. Please enjoy this fascinating organism without touching it."