The All Seeing Eye.
[The pyramid itself was seen as literally a stairway to the heavens. Egyptian rulers viewed themselves as Gods and the completed pyramid served as a symbol of their ascent to the above. The uncompleted pyramid such as that shown on the US dollar bill was a symbol of a country that was a work in progress. The “all seeing eye” would be borrowed from the Eye of Horus (an Egyptian god) and traditionally serves as a symbol of protection.]