According to the Chicago Zoological Society, a baby wombat is called a joey. Like kangaroos and opossums, wombats are marsupials. After just 21 days of development, a tiny wombat is born and must crawl from the birth canal to the mother's pouch, where he remains for six to eight months.
The University of Michigan states that, compared to other mammals, joeys are significantly underdeveloped at birth. If they make it to their mothers' pouches, much development must still take place. This includes the major organs: brain, heart, kidneys and lungs. One theory of this unusual form of reproduction suggests that the baby must leave the mother's uterus before being identified as foreign tissue and attacked by the mother's immune system.