The Collaborative International Dictionary of English v.0.48:

Lithodome \Lith"o*dome\ (-d[=o]m), n. [Litho- + Gr. do`mos
   house: cf. F. lithodome.] (Zool.)
   Any one of several species of bivalves, which form holes in
   limestone, in which they live; esp., any species of the genus
   Lithodomus.
   [1913 Webster]