Sea potatoes wash up en masse on Cornish beach

Marine experts say mysterious orbs found at Long Rock, near Penzance, are species of urchin stirred up from sandy burrows

Damien Gayle

Friday 19 August 201615.05 BSTLast modified on Friday 19 August 201618.12 BST

With their biomechanical, other-worldly appearance, these orbs look like baseballs reprocessed through the imagination of HR Giger. So their appearance en masse on a beach near Penzance this week left locals uneasy.

“I took one home with me, then panicked and put it in the bin in case it attacked,” said one dog walker who found hundreds on the beach at Long Rock, between Penzance and Marazion. His spaniel refused to go near them, he said.

Others reported finding the objects from Coverack to Looe. Jess Arnieson, 27, who was holidaying in the area, said people were baffled by the orbs. “There were hundreds of them stretching away as far as you could see along the shoreline,” she said. “The ones I saw were a bit smaller than a football but it’s possible there were some that were bigger ... I didn’t want to go any further along the beach.”

But there is no need to napalm the beaches of the west coast just yet. According to a marine biologist, the unsettling spheroids are not the vanguard of an invasion of Xenomorphs. They are a common species of urchin, known as sea potatoes or Echinocardium cordatum.

“They are quite common at the lower end of the right type of sandy beach, living below the sand in burrows,” said Martin Attrill, director of the marine institute at Plymouth University. “You get lots of them on Torbay main beach, for example. “They are related to starfish and usually covered with little spines.”

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