The term that refers to rocks produced when melted rock (magma) cools and hardens below the Earth's surface is igneous intrusive rocks.

Here's why:

* Igneous refers to rocks formed from the cooling and solidification of molten rock.

* Intrusive means the rock formed inside the Earth, as opposed to on the surface.

So, igneous intrusive rocks are formed from magma that cooled and solidified within the Earth's crust.