Which mammals lay leathery eggs?

TWO MAMMALS, the duck-billed platypus and the echidna (spiny anteater), do not give birth to live young. Instead, they are very primitive for mammals because, like reptiles and birds, they lay eggs rather than having live birth. They lay eggs that are protected by leathery shells. After laying eggs in the nest, the mother platypus warms the egg with her body for about ten days until they hatch. The females don’t have