Sailors have spotted a volcanic rock the size of Manhattan floating in the Pacific Ocean. Experts think this raft of pumice rock could help restore the Great Barrier Reef in Australia, which has sustained significant coral damage because of climate change.

Pumice Rock Spotted Days After Underwater Volcanic Eruption

The pumice rock was first spotted by the crew of the Australian adventure catamaran ROAM on Aug. 9 just days after the eruption of an underwater volcano near the Pacific Island of Tonga.

The crew found themselves in the midst of a huge mass of floating rocks that they said completely covered the ocean surface.

"The whole ocean was matte -- we couldn't see the water reflection of the moon," ROAM crew Larissa Hoult told CNN.

Massive Raft Of Volcanic Rock

The pumice is pockmarked by holes and cavities. It also floats like an iceberg. Only about 10 percent of its body is above water, while the rest is underwater.

Queensland University of Technology professor Scott Bryan, who specializes in geology and geochemistry said the raft moves at about 6 to 19 miles per day, with the surface currents, waves, and winds largely driving its speed and direction.

May Help Restore The Great Barrier Reef

The massive rock is expected to pick up marine species such as crabs and corals as it drifts in the ocean. Experts think this could help replenish some of the lost marine life in the world's largest reef system.

The raft is expected to drift through to the Australian coast over the next seven to 10 months, and bring with it a community of reef building organisms.

"At the moment the pumice will be bare and barren but over the next few weeks it's going to start getting organisms attached to it," Bryan said.

"Each piece of pumice is a rafting vehicle. It's a home and a vehicle for marine organisms to attach and hitch a ride across the deep ocean to get to Australia."