 It is known as sumsum in the Kalam language of Papua New Guinea.The long-tailed pygmy possum has large eyes, mouse/rodent-like ears, a pouch that opens anteriorly, and a tail that is about one and a half times as long as the body, giving the possum its name.Not much is known of this possum's behaviour, but what is known is that this species is both nocturnal and arboreal.