This is a fragment with three worked surfaces. It is the lateral cross-section of the front and back left of a shoulder and a portion of the pectoral on the front and the beginning of the back pillar on the back.
From Nubia (Sudan), Kerma, K III hall A. 1913: Excavated by the Harvard University–Boston Museum of Fine Arts Expedition; assigned to the MFA by the government of Sudan.
Harvard University—Boston Museum of Fine Arts Expedition