<P> Limpets are aquatic snails with a shell that is broadly conical in shape and a strong, muscular foot . </P> <P> Although all limpets are members of the class Gastropoda, limpets are highly polyphyletic, meaning that the various groups that we call "limpets" have descended independently from different ancestral gastropods . This general category of conical shell is technically known as "patelliform", meaning dish - shaped . Some species of limpet live in fresh water, but these are the exception . All members of the large and ancient marine clade Patellogastropoda are limpets, and within that clade the family Patellidae in particular are often called the "true limpets". </P> <P> 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, the "keyhole limpet" family, which is part of the clade Vetigastropoda (many other members of the Vetigastropoda do not have the morphology of limpets) and the Siphonariidae, the "false limpets", which use a siphon to pump water over their gills . </P>

What is a limpet and where does it live
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