the world > animals > invertebrates > subkingdom Metazoa > grade Triploblastica or Coelomata > class Pelecypoda or Conchifera > [noun] > section Asiphonida > family Aviculidae > genus Malleus > member of (3)
the hammer-shaped shell of a bivalve mollusc of the genus Malleus; (also) the animal itself (also called hammer-oyster).
= hammer-oyster n. at hammer, n.1 compounds 3; cf. malleus, n. 3.