Bivalve oyster shell
Devil’s Toe Nail
Here is the ‘classic’ bivalve shell from the Blue Lias around Lyme Regis. This is not, as folklore might have it, the gnarled toe nail from some long lost monster; it is in fact a humble and common oyster! It sat on the sea bed with the larger heavier shell acting as an anchor (the specimen on the right is in this position). The smaller shell sprang open just enough for the animal to be able to draw water inside to filter for food.
Find out more about bivalves on the molluscs pages.