Which mammals reproduce by laying eggs?

The only mammals that reproduce by laying eggs are the monotremes. These are a group of primitive mammals found only in Australia and New Guinea.

Here are the five species of monotremes:

* Echidnas: There are four species of echidnas, known for their spiny bodies and long snouts.

* Platypus: This is the most well-known monotreme, famous for its duck-like bill and webbed feet.

While they lay eggs, monotremes still share many characteristics with other mammals, such as having fur and producing milk to feed their young.