Wombats have pouches that face backward to keep dirt away from their babies while they dig.

Wombats are marsupials from Australia that live in large underground tunnels. They use strong claws to dig burrows that can be 30 meters long. Most marsupials have pouches that open at the top. If a wombat had a top-opening pouch, it would act like a shovel and fill with dirt while the mother worked.A backward-facing pouch keeps the baby, called a joey, clean and safe. Joeys are born after only 20 to 30 days and are the size of a jellybean. They stay inside the pouch for six to seven months to grow. The mother has special muscles to tighten the pouch opening so the baby does not fall out.Wombats also have a hard plate of cartilage in their rear ends. They use this tough backside to block the entrance of their tunnels from predators. If an animal like a dingo tries to get in, the wombat can crush the predator's head against the tunnel roof using its rump. The backward pouch stays protected behind this tough shield.