Babirusa Tusks Can Pierce Their Own Skulls

Babirusas resemble a wild boar that someone tried to sketch from memory after only passingly witnessing one. They are indigenous to some of Indonesia and are occasionally referred to as deer pigs. Male babirusas are distinguished by their exceptionally long, curved tusks. They have two sets of two, not just one, unlike a boar. They have a pair of canine tusks on their upper jaw that curve upward in addition to the typical set that protrudes from their lower jaw.

These tusks really penetrate through the animal's snout flesh; they do not extend up outside of their mouths. They are the only mammal in the world that has teeth that grow this vertically, as far as we know. This animal's tusks have the potential to be fatal complications. Growing inward, they eventually reach up and cover its eyes. The babirusa needs to use either rocks or trees to wear those tusks down. If it doesn't, the tusks have the potential to turn back and pierce the skull, killing the animal.