Very occasionally a lump of wood will come loose from an underwater crevice in the Mediterranean and float north towards the UK.
John Jennings, an amateur photographer, came across the 4ft long log covered in barnacles while out walking along the seafront at Boscombe in Bournemouth, Dorset.
He said: “I was out on my morning bike ride and the weather was awful so it was really quiet.
“At first I thought the object was a beached animal but when I got closer I saw that it wasn’t.
“It looked like an alien with all these little legs sticking out of the shells.
“The beach was deserted so I spent a good while taking pictures of them.
“It was only when I got home that I found out how rare they are.
“I headed back out with my proper camera and took some more photos with the pier in the background.
“It was just a really surreal experience being on this quiet beach with such strange creatures.”