资料来源 : Webster's Revised Unabridged Dictionary (1913)

Bubble shell \Bub"ble shell`\ (Zo["o]l.)
   A marine univalve shell of the genus {Bulla} and allied
   genera, belonging to the Tectibranchiata.

资料来源 : WordNet®

bubble shell
     n : marine gastropod mollusk having a very small thin shell