A piece of planet Mars. This is an exceptionaly large martian meteorite, one of less than 70 known.
Apparently, 11 millions years ago, an asteroid impact on mars was powerfull enough to send pieces of the planet into space. Some of this material landed on earth as meteorites.
It is now certain that this rock is a piece of mars since its chemistry has been compared to information provided by space probes.
This particular meteorite landed in Egypt.