[Cephalopoda] Muscular, suction-cup structure on the arms and tentacles (rarely on the buccal membrane) of cephalopods; some are stalked, placed on muscular rods that contract (squids and cuttlefishes); some are sessile, embedded without stalks on the oral surface of the arms (octopuses); they are usually counted either in longitudinal or in transverse (oblique) rows.