Wombats use their armored butts to block burrow entrances.

Perhaps no animal takes the phrase “butt out” more literally than the wombat. These creatures use their armored rumps to create an impenetrable barrier at the entrance of their burrows, thus keeping potential predators from invading their space.

Wombat rear ends feature a thick, tough fascia plate made of cartilage with minimal nerve endings, so even if a predator bites or claws at it, the wombat isn’t likely to feel pain. Their hardened butt is then covered by a layer of short fur, so the predator isn’t able to snatch onto the fur and pull the wombat out of its burrow. If a predator does manage to peek its head beyond the butt and into the burrow, wombats are known to pivot from using their butts as shields to blunt weapons, bashing the invader’s skull against the burrow’s dirt walls.