The rock group formed by the solidification of magma is called igneous rock.

Here's why:

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

* Igneous: The term "igneous" comes from the Latin word "ignis," meaning "fire."

* Solidification: When magma cools and hardens, it forms igneous rock.

There are two main types of igneous rocks:

* Intrusive igneous rocks: Formed when magma cools and solidifies slowly beneath the Earth's surface. They have large crystals.

* Extrusive igneous rocks: Formed when lava (magma that has erupted onto the Earth's surface) cools and solidifies quickly. They have small crystals or no crystals at all.