This is an Eye of Horus (wedjat) amulet. The details of the brow, eyeline and pupil are painted black. It is pierced lengthwise.
From Egypt, Giza, surface debris east of GI-C, south of Room R of Isis Temple. 1926: Excavated by the Harvard University–Boston Museum of Fine Arts Expedition; assigned to the MFA by the government of Egypt University-Museum of Fine Arts Expedition
Harvard University—Boston Museum of Fine Arts Expedition