Univalve
Part of speech: adjective
Definition: having one valve, typically used to refer to mollusks. consisting of a single valve or piece, used to refer to a shell.
Part of speech: noun
Definition: A univalve mollusk or its shell.
Gastropod
Part of speech: noun
Definition: Any member of a class of mollusks (Gastropoda) that includes snails and slugs; univalve mollusk.