LONDON — (CNN) A large chunk of debris from a SpaceX rocket has been found floating off a remote British island, more than 4,000 miles (6,500 kilometers) from where it exploded after takeoff.

The barnacle-encrusted debris — which measures about 33 feet by 13 feet (10 meters by 4 meters) and is decorated with a U.S. flag — is believed to have come from an unmanned Falcon 9 rocket, designed by Elon Musk’s private aerospace company.

The rockets are launched from Cape Canaveral in Florida. But the object was found off the Isles of Scilly, a small archipelago southwest of the British mainland.

The words “Falcon 9” were visible on the debris, said Joseph Thomas, a boat captain who spotted the wreckage in the waters between Bryher and Tresco in the Isles of Scilly on Thursday afternoon.

“My first thoughts were, it might be a whale or something dead floating on the surface, because there were seabirds feeding off it,” said Thomas, a skipper for Tresco Boat Services. “It turned out they were feeding off goose barnacles.”

Writing appeared to be visible on the debris, so there were fears it could have come from a plane. The reality was even more remarkable.

“Once we got it ashore with the help of another vessel, (the coastguard) scraped some of the goose barnacles off, and it just so happened the first place they scraped, they found the flag,” Thomas said.

Martin Leslie, coastal area commander for the coastguard, said in a statement that the debris “seems most likely to be (from) the unmanned Space X Falcon 9 which blew up shortly after takeoff from Cape Canaveral in June.”

That rocket had been on a resupply mission to the International Space Station, carrying more than 2 tons of goods, including 1,500 pounds of food and provisions for the three astronauts there.

At the time, it was the third spacecraft to fail to resupply the International Space Station in months.

SpaceX has not responded to a request for comment.

Local resident Pete Hicks, who was involved in bringing the debris to shore, tweeted, “Towed in and beached a piece of flotsam earlier. Thoughts were could be aviation parts… didn’t imagine space race.”

The debris is now on a beach on the island of Tresco, where authorities were checking it for serial numbers and liaising with SpaceX to identify which mission it had come from.

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