slipper limpet Crepidula fornicata, a small N. American mollusc which inhabits a single shell but does not otherwise resemble a limpet. It has a ‘half-deck’ inside its shell, and is sometimes called boat shell.
The slipper limpet preys on oysters. It was accidentally introduced to S. England along with some American oysters in 1890, and is now established there. The pestilential character of the species would be mitigated if it was more widely realized that it is good to eat, raw or cooked. Some were harvested and eaten in Britain and the Netherlands during the Second World War; but in normal times the difficulty of securing an acceptably high yield of meat from the creatures precludes their commercial exploitation, helpful though this would be to the oyster population.