This highly distinctive bivalve shell comes from the Corallian, Upper Jurassic, rocks around Osmington. It’s called Myophorella, but used to be known as Trigonia because of the distinctive triangular shape of the shell. It was reclassified when researchers reviewed the group and this reflects the constant refinements made in science. When it was first described, people did not know all of the similar fossils but as those collections grew, new researchers had the opportunity to re-group and re-name them. As a result, some names have been lost. Sometimes the old name is referred to in brackets to help avoid confusion, for example, Myophorella (Trigonia) clavellata.
Find out more about bivalves on the molluscs pages.