Fissurellidae, common name the keyhole limpets and slit limpets, is a taxonomic family of limpet-like sea snails, marine gastropod molluscs in the clade Vetigastropoda.Their common name derives from the small hole in the apex of their cone-like shells. Although superficially resembling other "true" limpets, they are in fact not closely related to them. Fissurellidae is the only family in the superfamily Fissurelloidea.