In archaeological parlance, a pyramidion, (pl. pyramidia), is the uppermost piece, or capstone, of an Egyptian pyramid.
Very few pyramidia have survived to modern times. Most of those that have are made of polished black Granite inscribed with the name of the pyramid's owner. A total of four pyramidia - the world's largest collection - is housed in the main hall of the Egyptian Museum in Cairo. Among them is the pyramidion from the so-called Black Pyramid of Amenemhet III at Dahshur.
A badly damaged red granite pyramidion thought to have been created for the Red Pyramid of Sneferu at Dahshur has been reconstructed and is on open-air display beside that pyramid - however it presents a minor mystery as its angle of inclination is steeper than that of the edifice it was apparently created to surmount.
The scene depictions typically refer to the course of the sun, rising on one lateral face, setting on the opposite face, and traveling through the night, through the underworld, ruled by Osiris.
The pyramidion of Scribe Moses (mes,s), (New Kingdom, 19th Dynasty, ca 1250 BC, limestone, .53 m tall) has himself, in offering pose, with his name, on two opposite faces. The adjacent opposite faces, have a babboon: "Screeching upon the rising of the Sun, and the Day". (The babboon is also the god-scribe representation of the scribe, in the God Thoth, so a dual usage, and obvious, for Scribe Moses.) See Ref., Peck.
The pyramidion of Ptahemwia, (19th Dynasty, Ramesside Period, ca 1200 BC, limestone, .28 m wide, .42 m tall), likewise has sun-related scenes. The Sun God Re-Horakhti, and the god of the Underworld Osiris are on one lateral face. Facing the two Gods, on the adjacent lateral face is the standing deceased, in a offering pose, and he is also standing, facing 3-columns of hieroglyphs. See Ref., Schulz, Seidel.