Magma that hardens and comes to the Earth's surface is called extrusive igneous rock.

Here's why:

* Igneous rock is any rock formed from the cooling and solidification of magma or lava.

* Magma is molten rock found beneath the Earth's surface.

* Lava is magma that has erupted onto the Earth's surface.

* Extrusive refers to the process of igneous rock formation where magma erupts onto the Earth's surface.

So, when magma reaches the surface, it's called lava, and when that lava cools and solidifies, it forms extrusive igneous rock.