It can be distinguished from other members of the genus by the number of claws on the fore and hind feet. It has five claws on its fore feet and four on its hind feet. The adult animal weights between 5 kg (11 lb) and 10 kg (22 lb). Its body length ranges from 60–100 cm (23.5-39 inches). It has no tail. It has dense black fur. The species is the largest monotreme and is slow moving. It rolls into a spiny ball for defense.