Researchers from the University of Central Lancashire in Preston said that conditions on the island make it optimal for the earthworms.

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They discovered worms up to 15 inches in length.

The worms have no predators, which means they have had room to grow larger as they evolved.

Kevin Butt, a professor at the university who led the study, said he first noticed large worm burrows in 2005. "So I had my suspicions that there may be some pretty big worms in the area," he said.

"There are still unanswered questions and we plan to continue our research to find out as much as possible about these creatures."

The worms can live for nearly a decade, whereas other, smaller earthworms may only live two years.