During an expedition aboard NOAA's Okeanos Explorer at a depth of 7,000 feet, scientists discovered a sponge that measured 12 feet long and 7 feet wide. (NOAA Office of Ocean Exploration and Research)

The deep sea is dark and full of mysteries.

Way below the water's surface north of the Hawaiian islands, a remotely operated vehicle has spotted a massive creature hitherto unknown to science.

The ROV captured footage of the spectacularly large sponge during a National Oceanic and Atmospheric Administration deep-sea expedition, and the species was identified for the first time in a study published Thursday in the journal Marine Biodiversity.

According to NOAA, the "sponge the size of a minivan, the largest on record," measured 12 feet long and seven feet wide.

Prior to this discovery, the largest recorded sponge was one discovered in shallow waters off western Canada in the late 1800s. It measured about 11 feet long and just over three feet wide.

And there's more to this sponge than its girth: It could also be among the oldest living animals on earth. (Yes, here is your obligatory reminder that, while sponges may look like weird underwater plants, they belong to the animal kingdom.)

Sponges can live for hundreds or even thousands of years. "While not much is known about the lifespan of sponges, some massive species found in shallow waters are estimated to live for more than 2,300 years," the study authors write.


A sponge the size of a minivan, the largest on record, was found in summer 2015 during a deep-sea expedition in the Papahānaumokuākea Marine National Monument off Hawaii. (NOAA)

The sponge was discovered last summer in the Papahānaumokuākea Marine National Monument, a 140,000 square-mile marine conservation area.

“Finding such an enormous and presumably old sponge emphasizes how much can be learned from studying deep and pristine environments such as those found in the remote Papahānaumokuākea Marine National Monument," Daniel Wagner, Papahānaumokuākea research specialist, said in a statement.

Wagner told New Scientist he estimates the sponge to be around 1,000 years old.

"Sponges don’t have things like growth rings that can be used to estimate age,” Wagner said. “We do know, however, that several coral species that live at those depths can live to multiple hundred to even a few thousand years: the oldest one is 4,500 years."

Christopher Kelly, NOAA research scientist and co-lead for the expedition, said the sponge "just appeared" on the ROV's high-definition camera, Australia's Pacific Beat radio reported.

"We were looking for deep water corals and sponges, and we had just gotten some close ups of some corals, then turned away to continue the survey and the sponge appeared out of nowhere," he told the outlet.

And "it looked like a folded blanket," he added. "It looks as though somebody took a blanket and draped it over a chair... so that's what we called it until we got a better name for it, the folded blanket sponge."

That this deep-ocean sponge doesn't appear to have been disturbed may have allowed it to become so large. “A lot of organisms in deep seas grow very slowly, so they need their habitats to remain stable over a long time to be able to grow larger and larger,” Wagner told New Scientist.

This particular organism wasn't sampled. But a sample was collected nearby during a previous expedition of what researchers believe to be the same species, belonging to the Rossellidae family of sponges.

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