This amulet of polished hematite represents a headrest. Such amulets were common in Late Period burials, where their magic was intended to lift the head of the deceased at the moment of resurrection.
From Egypt, Giza, G 7757 A, (tomb of Kheperre) room IV. 1929 : excavated by the Harvard University–Museum of Fine Arts Expedition; assigned to the MFA in the division of finds by the government of Egypt.
Harvard University—Boston Museum of Fine Arts Expedition