Several varieties of monotremes are also subject to extinction without assistance from organizations and government agencies. The surviving genera of monotremes includes the duck-billed platypus and the Australian and New Guinea anteaters. All lay eggs. Soft, leathery shells and a pouch distinguish them. Once their babies are born, some continue to grow in a temporary pouch. Although the monotremes have fur that evolved to help maintain body temperature, the temperature regulating mechanism in the brain is imperfect; as a result ,they tend to be cooler and have more variable body temperature than higher mammals. Monotremes die because of continuous deforestation which destroys their natural habitat.