Possibly made by cutting off the top of a cartouche.
From Nuri, pyramid 47 (Queen unknown), northwest foundation deposit. 1918: excavated by the Harvard University-Museum of Fine Arts Expedition; assigned to the MFA by the government of Sudan.
Harvard University—Boston Museum of Fine Arts Expedition
Nubian, Napatan Period, reign of Amanastabarqa, 510–487 B.C.