What is "fan shell"

Scallop \Scal"lop\ (?; 277), n. [OF. escalope a shell, probably of German or Dutch origin, and akin to E. scale of a fish; cf. D. schelp shell. See Scale of a fish, and cf. Escalop.] [Written also scollop.]

1. (Zo["o]l.) Any one of numerous species of marine bivalve mollusks of the genus Pecten and allied genera of the family Pectinid[ae]. The shell is usually radially ribbed, and the edge is therefore often undulated in a characteristic manner. The large adductor muscle of some the species is much used as food. One species ( Vola Jacob[ae]us) occurs on the coast of Palestine, and its shell was formerly worn by pilgrims as a mark that they had been to the Holy Land. Called also fan shell. See Pecten,

2. Note: The common edible scallop of the Eastern United States is Pecten irradians; the large sea scallop, also used as food, is Pecten Clintonius syn. Pecten tenuicostatus.

   2. One of series of segments of circles joined at their extremities, forming a border like the edge or surface of a scallop shell.

3. One of the shells of a scallop; also, a dish resembling a scallop shell.