What is "trumpet shell"

Triton \Tri"ton\ (tr[imac]"t[o^]n), n. [L., fr. Gr. Tri`twn.] (Gr. Myth.) A fabled sea demigod, the son of Neptune and Amphitrite, and the trumpeter of Neptune. He is represented by poets and painters as having the upper part of his body like that of a man, and the lower part like that of a fish. He often has a trumpet made of a shell.

Have sight of Proteus rising from the sea, Or hear old Triton blow his wreathed horn.
--Wordsworth.

2. (Zo["o]l.) Any one of many species of marine gastropods belonging to Triton and allied genera, having a stout spiral shell, often handsomely colored and ornamented with prominent varices. Some of the species are among the largest of all gastropods. Called also trumpet shell, and sea trumpet.

3. (Zo["o]l.) Any one of numerous species of aquatic salamanders. The common European species are Hemisalamandra cristata, Molge palmata, and Molge alpestris, a red-bellied species common in Switzerland. The most common species of the United States is Diemyctylus viridescens. See Illust. under Salamander.