Stones With Holes at Charmouth Beach 8 – Beach stone with holes made by marine invertebrates at Charmouth, Dorset, England. The larger rounder holes have been made by boring bivalve molluscs such as the Common Piddock (Pholas dactylus) or the Wrinkled Rock Borer (Hiatella arctica); and the smaller holes by marine polychaete worms like the Polydora spp.
Jessica's Nature Blog 