It is believed that pyramids evolved from the mastaba constuction (mudbrick) of earlier tombs and the Egyptians began to stack the mastaba resulting in the pyramid formation. They also linked the pyramids to the cardinal points and belived the pyramid image was a symbol of the rays of the sun (or so I'm told) and therefore Ra. However, the mastaba tombs had hieroglyphics that seems not to of been repeated in later times and larger structures. Any ideas as to why?