The Collaborative International Dictionary
Bubble shell
Bubble shell \Bub"ble shell`\ (Zo["o]l.) A marine univalve shell of the genus Bulla and allied genera, belonging to the Tectibranchiata.
Wiktionary
bubble shell
n. 1 (context malacology English) A marine univalve shell of the genus (taxlink Bulla genus noshow=1) and allied genera, belonging to the ''(taxlink Tectibranchiata suborder noshow=1)'' molluscs. 2 The (vern: headshield slug)s of genus (taxlink Bulla genus noshow=1), belonging to the clade ''(taxlink Cephalaspidea clade nowshow=1)'' of gastropods.
WordNet
bubble shell
n. marine gastropod mollusk having a very small thin shell