Pyramidion

A pyramidion (plural: pyramidia) is the capstone of an Egyptian pyramid or the upper section of an obelisk. Speakers of the Ancient Egyptian language referred to pyramidia as benbenet  and associated the pyramid as a whole with the sacred benben stone.

Pyramidia were usually made of limestone, sandstone, basalt or granite, and were sometimes covered with plates of copper, gold or electrum. From the Middle Kingdom onward, they were often "inscribed with royal titles and religious symbols".