This is a large clam-like shell. The stronger growth lines may be annual lines making this specimen perhaps five or six years old.
Horn Park Quarry near Beaminster is the smallest National Nature Reserve (NNR) in Britain, being just one acre or 0.32 hectares in size. It was once a working quarry but it is no longer and the remaining outcrop is protected by a fence. There is no collecting other than for scientific and educational purposes. A section of the fossil beds has been stripped back and protected from the weather by a removable cover. To arrange a visit, contact the Senior Reserve Manager on 07899 731404.
Find out more about bivalves on the molluscs pages.