Why have the pyramids of egypt survived whereas the ziggurats of mesopotamia have not?

Ziggurats are, architecturally, the Mesopotamian equivalent of the Egyptian pyramids: large artificial square mountains of stone. They were built using different materials. The pyramids were built from stone and the ziggurats from mud brick. This would have caused the Mesopotamian bricks to fall apart and break more easily, as for the Egyptian bricks were stable, stronger and durable. Hope I helped. :)