Kalmar "chelonian reptile" tana nufin duk wani abu mai rarrafe wanda ke cikin tsari na Chelonia, wanda ya haɗa da kunkuru, kunkuru, da terrapins. Wadannan dabbobi masu rarrafe suna da nau'in bawo na musamman, wanda ya ƙunshi harsashi na sama (carapace) da ƙananan harsashi (plastron) waɗanda aka haɗa tare. Chelonians dabbobi ne masu jin sanyi kuma suna da jinkirin metabolism. An kuma san su da tsayin daka, tare da wasu nau'ikan suna rayuwa sama da shekaru 100.