Fibula pieces are obtained as a drop from Dagannoths and Wallasalkis, found underneath Waterbirth Island. Along with a skull piece, a ribcage piece, 6 dagannoth hides, and 22 000 coins, a fibula piece can be traded to Peer the Seer for full skeletal armour. The fibula piece alone along with 2 hides and 7500 coins can be traded for skeletal bottoms.