The mammal known for laying eggs is the monotreme called the platypus. Native to Australia, the platypus is a unique species that exhibits features uncommon in mammals, such as a duck-bill, webbed feet, and the ability to lay eggs instead of giving live birth, unlike most mammals. The platypus plays a crucial role in its habitat, feeding on aquatic invertebrates and using its electroreception to find food. Its unusual reproductive method, along with its other distinctive characteristics, makes the platypus an interesting subject of study in the field of biology and evolutionary research.