What mammals are not born alive but hatch from an egg?

The mammals that are not born alive but hatch from an egg are called monotremes.

There are only five species of monotremes in the world, all found in Australia and New Guinea:

* The echidnas: There are four species of echidnas, which are spiny anteaters.

* The platypus: This unique mammal is the only surviving member of its family.

These animals share some features with reptiles, like laying eggs, but they are still classified as mammals because they nurse their young with milk.