In the Gulf of Mexico, a strange creature lurks in the deep: a blood-red squid with stubby arms, missing tentacles, and a knack for swimming like a nautilus.

The unusual squid, which might or might not be a new species, was filmed on April 17 by the crew of the Okeanos Explorer, a research vessel run by the U.S. National Oceanic and Atmospheric Administration.

But on April 17, researchers got a surprise: Thousands of feet beneath the surface in the western Gulf of Mexico, the Okeanos Explorer's remote-controlled submarine spotted a creature that, at first, didn't resemble a squid at all.

“You get a lot of octopuses that are sitting on the ground and being adorable,” says squid biologist Sarah McAnulty, a Ph.D. student at the University of Connecticut. “This one looks more like a vampire squid in color, but then it has this completely bizarre body pattern that just totally bowled me over. It almost looks like a nautilus in the way it's swimming.”

“My first reaction was, 'What in the hell was that?',” says NOAA biologist Mike Vecchione, a squid expert featured on the live Okeanos feed. “It didn't look like any squid I had seen, until we started getting close and the animal started rotating around.”

Vecchione and McAnulty say that it's too soon to say what the mystery squid is. Perhaps it's a new species, but Vecchione is currently checking whether the mystery squid is Discoteuthis discus, a squid species known from fragments collected in trawls throughout the tropical Atlantic.

“Every time we catch [D. discus], it's so hard to tell what species it is. I've never seen one entire, or in good condition,” says Vecchione. “If that's what it is, then it's the first time anybody's seen one alive.”

A Deepening Mystery

The submarine didn't collect the squid, so for now, biologists must speculate on the creature's anatomy and behavior. What does the squid eat? Does it bioluminesce, like many deep-sea creatures? And what's with the animal's strange posture?

Perhaps the unfamiliar submarine spooked the squid into scrunching up: Researchers say that it's not unheard of for a squid to adopt a similar posture as a form of defense. However, this mystery squid stands out. “This one was real extreme,” says Vecchione. “A couple of the arms were folded right flat on the back, and a couple were folded underneath, and a couple were sticking out to the side.”

McAnulty suggests that beyond defense, the squid's posture could help it collect “marine snow”—the detritus from shallower waters that many deep-sea creatures depend on for food.

Some squids, such as the Hawaiian bobtail squid, have sticky skin that allows them to collect marine snow on their outstretched bodies. Perhaps the squid's arms help harvest marine snow, or help prevent the nutritive schmutz from flowing off the creature's body as it swims?

“This would be a really bizarre approach to surviving,” says McAnulty. “This is total conjecture, but it seems plausible.”

McAnulty and Vecchione say that future dives may reveal more details. Vecchione wants to see the animal's underside, while McAnulty wants to see them film the creature without lights, to check whether the squid bioluminesces.

Both agree that the squid will hardly be the last surprise awaiting marine biologists.