Seatown Rock Piddock Holes 1 – Rounded holes up to 2cm in diameter marking the burrows of the marine bivalve mollusc called the piddock (Pholas dactylus Linnaeus) in calcareous mudstone belonging to the Belemnite Marl Member of the Charmouth Mudstone Formation at Seatown beach in Dorset, England. Much smaller almost dumbbell-shaped holes frequently occur around the piddock holes, marking the burrows of marine bristleworms such as the as those created by the Polydora species.
Jessica's Nature Blog 