Limpets are single-shelled molluscs, looking like small pyramids, which are found attached to rocks. You need to have good eyes to spot them and a knife with a pointed tip to detach them. As long as you know it has come from unpolluted waters, you can eat this shellfish raw with just a few drops of lemon juice. Limpets have a very nutty flavour and are delicious in fish soups. The best dish I ever tasted with limpets was a truly memorable linguine with mussels and limpets at the Cambusa restaurant in Positano.