Monotremes are the strangest of mammals

Nor do monotremes, the third and arguably strangest example of mammalian birth.There were once hundreds of monotreme species,but there are only five left:four species of echidnas and the duck-billed platypus.The name monotreme means one hole referring to the single orifice they use for reproduction,excretion,and egg-laying.Like birds,reptiles,fish,dinosaurs,and others,these species lay eggs instead of giving birth to live young.Their eggs are soft-shelled,and when their babies hatch, they suckle milk from pores on their mother's body until they're large enough to feed themselves.