A limpet is an aquatic snail with a shell that is broadly conical in shape. "Limpet" informally refers to any gastropod whose shell has no obvious coiling, like the coiling which can be seen in the shells of garden snails or winkles. Other groups, not in the same family, are also called limpets of one type or another, because of the similar shapes of their shells. Examples include the Fissurellidae, which are known as the "keyhole limpet" family. This family is part of the clade Vetigastropoda, however, many other members of the Vetigastropoda do not have the morphology of limpets.