pholas

from WordNet (r) 3.0 (2006)

Pholas
    n 1: type genus of the family Pholadidae: piddocks [syn:
         {Pholas}, {genus Pholas}]

from The Collaborative International Dictionary of English v.0.48

Pholas \Pho"las\, n.; pl. {Pholades}. [NL., fr. Gr. fwla`s,
   fwla`dos, a kind of mollusk.] (Zool.)
   Any one of numerous species of marine bivalve mollusks of the
   genus {Pholas}, or family {Pholadid[ae]}. They bore holes for
   themselves in clay, peat, and soft rocks.
   [1913 Webster]