The Quokka (Setonix brachyurus) is a small, vulnerable marsupial from Western Australia, famous for its "smiling" expression . This nocturnal herbivore feeds on grasses and leaves, and can climb small trees. While thriving on predator-free islands like Rottnest, mainland populations have declined due to habitat loss and introduced predators. It's a social animal that gets most hydration from its food, highlighting the need for conservation efforts.