By Damien Gayle

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

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.