Gryphaea, common name devil’s toenails, is a form of extinct oyster. These fossils range from 200 million years ago to the Triassic to mainly the Jurassic period and are common in many parts of Britain.
These oysters lived on the seabed in shallow waters, in large colonies. The complete fossils consist of two articulated valves: a larger gnarly shaped shell (the “toenail”) and a smaller, flattened shell, the “lid”. The soft parts of the animal occupied the cavity between the two shells. The shells also feature prominent growth bands. The larger, curved shell sat within the mud on the sea floor
The bivalve Gryphaea was nicknamed the Devil’s Toenail because its of its curved shape, marked with prominent growth bands. This resembles a thick toe with a toenail. It was believed these were made as the Devil clipped his toenails and were believed to cure arthritic joint pains.
Mary Anning discovered many Gryphaea when she was foraging for fossils on the beaches around Lyme Regis. Devil’s toenails are particularly common in the Lower Jurassic rocks around Scunthorpe. Iron ore was quarried locally and across the midlands (Northamptonshire to Warwickshire) and it is quite common to find Gryphaea in the quarries. In 1936 Scunthorpe’s coat of arms included two Gryphaea.
