This is part of a thumb of a left hand. The cuticle is carefully carved. The hand is grasping part of a large cylindrical object. Traces of black pigment remain.
From Nubia (Sudan), Kerma, K III 5(1). 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