The type of igneous rock that forms beneath Earth's surface is called intrusive igneous rock.

Here's why:

* Intrusive means that the magma (molten rock) cools and solidifies *inside* the Earth's crust.

* Extrusive igneous rocks, on the other hand, form when lava (magma that erupts onto the surface) cools and solidifies.

Characteristics of Intrusive Igneous Rocks:

* Slow cooling: Magma cools much slower than lava because it's insulated by surrounding rock.

* Large crystals: Slow cooling allows for the formation of large, well-defined mineral crystals.

* Examples: Granite, gabbro, diorite

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