Pyramidion

A pyramidion (plural pyramidia) is the very top piece of an Egyptian pyramid. They were called "benbenet" in the Ancient Egyptian language. In Egypt's Old Kingdom, pyramidia were made of diorite, granite, or limestone. These were then covered in gold or electrum. The gold would reflect the rays of the sun. In later times they were made from granite which had royal titles and religious symbols cut into them.
Very few pyramidia still exist. Most of those that have are made of polished black granite, with the name of the pyramid's owner cut into them. There are four pyramidia on show in the main hall of the Egyptian Museum in Cairo. They include the pyramidia from the Black Pyramid of Amenemhat III at Dahshur and the Pyramid of Khendjer at Saqqara.
A badly damaged white Tura limestone pyramidion is thought to have been made for the Red Pyramid of Sneferu at Dahshur. It has been rebuilt and put on show at the side of the pyramid. However it does not match, as its angles are steeper than that of the sides of the pyramid.
Private brick pyramids with pyramidia.
During the New Kingdom, some private underground tombs had a small brick pyramid built on top of them. These pyramids were topped with a pyramidia. The four sides included texts and scenes about the cult of the Sun god Ra.
The scenes usually show the course of the sun. It is shown rising on one side, and setting on the opposite side, and traveling, through the night, through the underworld, ruled by Osiris.
Scribe Moses pyramidion.
The pyramidion of the scribe Moses was made about 1250 BC from limestone. It is 53 cm tall and shows him making an offering, with his name, on two opposite sides. The other two sides show a baboon which represents the god Thoth.
Ptahemwia pyramidion.
The pyramidion of Ptahemwia was made about 1200 BC, from limestone. It is 28 cm wide and 42 cm tall, and shows sun-related scenes. The Sun god, Ra, and the god of the Underworld, Osiris, are shown on one side. On another side is Ptahemwia, standing in an offering pose, facing three columns of hieroglyphs.