Shell-Shaped Inner Ear Part Needed for Hearing

Puzzle 1 of Groups of Three Easy Pack

Question is: Shell-Shaped Inner Ear Part Needed for Hearing

and the answer is: COCHLEA

Word Meaning:

COCHLEA — (anatomy) The complex, spirally coiled, tapered cavity of the inner ear of higher vertebrates, which contains the organ of Corti and in which sound vibrations are converted into nerve impulses.

Definitions from Wiktionary.