Here's why:

* Magma: Molten rock found beneath the Earth's surface.

* Cooling: As magma rises towards the surface or intrudes into existing rocks, it cools down.

* Crystallization: As the magma cools, the atoms within it begin to arrange themselves into a more ordered, crystalline structure.

* Igneous Rocks: These rocks are formed directly from the solidification of magma or lava (magma that erupts on the surface).

Let me know if you'd like to know more about igneous rocks!