This stone amulet represents the djed-pillar. The pillar, which symbolized the spinal column of the funerary god Osiris, was the hieroglyphic symbol for stability.
From Giza: G 7525 Y [Excav. date] July 1925. Excavated by the Harvard University–Museum of Fine Arts Expedition; assigned to the MFA by the government of Egypt.
Harvard University—Boston Museum of Fine Arts Expedition