Ancient Egyptian tombs became more complex over time.
In the pre-dynastic era, the deceased was wrapped in matting or goatskin before being placed in an oval pit dug in the sand. Food and drink in pottery vessels were left for the journey in the hereafter. Sand or rubble was heaped on top of the grave to form a small mound.
Later, tombs of nobles consisted of underground rectangular structures with one or more compartments. These were sometimes lined with brick to support the sides and were covered with heaps of rubble.
A Second Dynasty tomb, called a mastaba, consisted of an underground structure with a huge rectangular structure over it created around a core of stone and rubble. Its outer walls were built straight but leaning slightly inward.
In the Third Dynasty, the architectural genius Imhotep caused a revolution in funerary architecture by building a mortuary complex for King Djoser of stone instead of brick and timber.
The tomb began as an impressive 8 meter or 26 feet high square mastaba of 71.5 meters or 234.5 feet on each side. Two more additions were made until the mastaba became a rectangular 109 by 121 meters or 358 by 397 feet.
This mastaba rose in the next phase in four steps; later, two more steps were added. The flat-topped mastaba was changed into a step pyramid and reached a height of 62.5 meters or 205 feet.
From that time until the end of the Old Kingdom, this type of stone construction, called a pyramid, became the standard form for the royal tombs.
In ancient Egypt, the pyramid form was called "mer" and was given the shape of a triangle. The contemporary word "pyramid" was probably derived from the Greek "pyramis," which means a kind of cake.
With construction of the pyramid of King Senefru at Meidum, the transitional stage from the step pyramid to the true pyramid began. A step pyramid of eight steps was designed to become a true pyramid with a slope of 51 degrees, 50 minutes, and 35 seconds.
The courses were laid in inward leaning additions and were later regularly built. This method for building a pyramid became standard for the true pyramids of the Fourth Dynasty.