Babirusas live in wetlands and swamps within the rainforests of Indonesia's islands of Sulawesi, Togian, Sula, and Buru—and they are found nowhere else. Sulawesi babirusas are sometimes called "pig deer" because of adult males' unusual upper tusks, which grow right through the top of their snout. Both adult males and females have a pair of lower tusks, but only males have those distinctive uppers that look a bit like misplaced antlers.