Hinged-Shelled Mollusc
Puzzle 13 of Vienna Hard Pack
Question is: Hinged-Shelled Mollusc
and the answer is: BIVALVE
Word Meaning:
BIVALVE — Any mollusc belonging to the taxonomic class Bivalvia, characterized by a shell consisting of two hinged sections, such as a scallop, clam, mussel or oyster.
Definitions from Wiktionary.