A small to medium-sized, brown, grey, or white marsupial mammal with a long, prehensile tail, found in forest and scrub in Australia, New Guinea, and Sulawesi and introduced for fur production in New Zealand, where it is now a serious pest, and in China. It is named for its resemblance to the American opossum. Most possums are nocturnal and many are arboreal. They are herbivores, nectar-feeders, omnivores, or insectivores. There are 69 species comprising the suborder Phalangeriformes, and ranging 5–120 cm in length, but most are about the size of a domestic cat.