Search Result for "ark shell":
Wordnet 3.0

NOUN (1)

1. marine bivalve mollusk having a heavy toothed shell with a deep boat-like inner surface; 



The Collaborative International Dictionary of English v.0.48:

Ark shell \Ark" shell`\ (Zool.)
   A marine bivalve shell belonging to the genus Arca and its
   allies.
   [1913 Webster]


WordNet (r) 3.0 (2006):

ark shell
    n 1: marine bivalve mollusk having a heavy toothed shell with a
         deep boat-like inner surface