Skull

Skull is a collectible relic found in Shadow of the Tomb Raider. It is part of the Metamorphosis collection, acquired through the course of gameplay. Players must complete the Challenge Tomb in the Mission of San Juan, as well as its associated side mission.

Information
''An adhesive made of tree sap and powdered bone hold the jade and other gems in place within the wearer's teeth. A crude drill, perhaps made of obsidian, would have been used to delicately carve out the notches required to hold the jewelry in place.''