Rostellum /ˌrɑːˈstɛlʌm/ (meaning "small beak", from the Latin rostrum for "beak"; pl. rostella) in helminthology in a protruding part of the anterior end of tapeworms. It is a retractable, cone-like muscular structure that is located on the apical end of the scolex, and in most species is armed with hooks, the organs of attachment to the host's intestinal wall.[1] It is a parasitic adaptation in some cestodes for firm attachment in the gastrointestinal tract and is structurally different from one species to another (or even absent is some species), thereby becoming an important diagnostic feature.[2][3]