I had seen these shells on Studland beach for years and thought they were just cockle shells until one day I was browsing the books in the National Trust shop and found a copy of the RSPB Handbook of the Seashore. Next time I went walking along the beach I took more notice, or more to the point I took some photographs, and soon discovered that these small, smooth shells are all that remains of a bi-valve creature, thin tellin (Angulus tenuis).
Thin tellin shells are about an inch across and can be quite colourful in delicate shades of pink and orange but sadly this one had obviously been on the beach for sometime and lost its colouring. It is a smooth shell that has concentric rings and it the colouring comes in bands in line with the rings.
At sea the animal lives just under the surface of the sand where it partly emerges to siphon sea water for microscopic food when the tide is in and then it hides away when he tide goes out and uncovers it. It can live for up to en years if not predated.Angulus tenuis: thin tellin