Egg-laying mammals, known as monotremes, are a unique group of mammals that reproduce by laying eggs instead of giving birth to live young. The most well-known examples of monotremes are the platypus and the echidna. These animals possess characteristics of both mammals and reptiles, such as having fur and producing milk, but they also lay eggs like reptiles. Monotremes are primarily found in Australia and New Guinea. They have a cloaca, a single opening for excretion and reproduction, which is a trait shared with reptiles. Despite their small number, egg-laying mammals provide valuable insights into the evolution of mammals and their reproductive strategies.