What three MAMMLES lay eggs?

The three types of mammals that lay eggs are monotremes, which include the platypus and the echidna. Monotremes are unique among mammals as they reproduce by laying eggs rather than giving live birth. These mammals possess a cloaca, a single opening for excretion and reproduction, similar to reptiles and birds. The platypus is known for its duck-bill and webbed feet, while echidnas have spiny coats and are often called spiny anteaters.