Probably a one off and you know how I love alliteration as per the headline. Our wombat eats grass and other plant material. It is one of our marsupials, meaning when its very immature young are born they move to a pouch to develop into kiddie wombats.
Generally our marsupials have an upward facing pouch but as wombats live in ground burrows they dig themselves, imagine what would happen to a forward facing pouch as a wombat clawed away at the earth and threw the soil backwards. So as you can see from this video taken by Sarah Leighton, the wombat's pouch faces backwards. What a wonder is evolution!