This is a nearly rounded fragment of a limb of a medium-scale statue. The stone is black granodiorite, the break areas look almost melted (often with large pink feldspar veins or inclusions). GD4.
From Nubia (Sudan), Kerma, K X grave K 1087 debris. 1914: 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