Plenaster craigi grow on the nodules and are vulnerable if mining for nodules commences. “We have collected a few hundreds of this sponge species and they were only found attached to the nodules,” Dr. Lim said.

“The C.C.Z. is a soft sediment habitat so the hard surfaces are limited,” Dr. Beaulieu said. While almost nothing is known of Plenaster craigi – what they eat, how they reproduce, where they are distributed – most sponge species, like corals, have to find hard surfaces to settle down on and grow while they are young, she said.

But the C.C.Z. is so vast, Dr. Glover believes that it is more likely large areas would be left undisturbed. The International Seabed Authority has already reserved wide swaths of seafloor for protection and commissioned large-scale exploration studies to establish life on the seafloor. “To get to the point where you can make informed decisions, you need to know what animals live there,” Dr. Glover said.

More pressing are the huge sediment plumes that mining activities will generate, says Ann Vanreusel, a marine biologist at Ghent University in Belgium. That’s where Plenaster craigi could prove to be useful as an indicator species because of its abundance, she says. “Every animal you collect from the seafloor seems to be a different species,” Dr. Vanreusel said. An organism that will clearly be disturbed from the plumes and abundant enough to count such as Plenaster craigi could help researchers figure out the effects of deep-sea mining and perhaps even the possibilities for recovery, she said.

“They can almost act like a canary,” Dr. Amon said.

But the key, Dr. Hannington said, is that deep-sea mining may not be economically viable. “Nobody has proved it can be done,” he said. Many details, like whether the metals can be extracted from the marine ore, still need to be worked out, he said. “If it turns out that marine mining is not economically feasible, all of the other problems go out the window.”

Dr. Glover’s team first noticed Plenaster craigi while on the 2013 expedition to the exploration area allocated to the United Kingdom. “For three years we were calling them sponge species A,” Dr. Glover said. Then in 2015, Dr. Lim participated in the second expedition to the area allocated to Singapore and began working with Dr. Glover to identify and classify the sponges. Now, Dr. Lim has begun work on a second sponge species growing on the nodules, while Dr. Glover is preparing an extensive study on deep sea mollusks.

The researchers are racing against time to study life on the seafloor while being limited not only by sample collection, but also a lack of scientists with the expertise to characterize and classify new species, Dr. Beaulieu said. “It takes a lot of time, one by one by one, to describe a new species,” she said, “and there are still so many to go.”