lithophagous

from The Collaborative International Dictionary of English v.0.48
Lithophagous \Li*thoph"a*gous\, a. [Litho- + Gr. ? to eat.]
   (Zool.)
   (a) Eating or swallowing stones or gravel, as the ostrich.
   (b) Eating or destroying stone; -- applied to various animals
       which make burrows in stone, as many bivalve mollusks,
       certain sponges, annelids, and sea urchins. See
       {Lithodomus}.
       [1913 Webster]
    

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