A North American species which preys on the oyster. It is sometimes called boatshell, since it has a ‘half-deck’ inside its shell. It was accidentally introduced to southern England along with some American oysters in about 1890 and is now firmly established there. The pestilential character of this species would be mitigated if more people realized that slipper limpets are good to eat, either raw or cooked. Some were harvested and eaten in Britain and the Netherlands during the Second World War. But experiments at Gloucester, Mass., by Learson and others, have shown that there is no easy way of processing the creatures and producing an acceptably high yield of meat. A do-it-yourself seafood for the real enthusiast who wants to do the local oysters a good turn.