manta (n.)

very large ray (also called devilfish), 1760, from Spanish manta "blanket" (which is attested in English from 1748 in this sense, specifically in reference to a type of wrap or cloak worn by Spaniards), from Late Latin mantum "cloak," back-formation from Latin mantellum "cloak" (see mantle (n.)). The ray so called "for being broad and long like a quilt" [Jorge Juan and Antonio de Ulloa, "A Voyage to South America"].