Here's why:

* Igneous rocks are formed from the cooling and solidification of magma (molten rock) or lava (magma that has erupted onto the Earth's surface).

* Sedimentary rocks are formed from the accumulation and cementation of sediments, which are fragments of other rocks, minerals, or organic matter.

* Metamorphic rocks are formed when existing igneous or sedimentary rocks are transformed by heat, pressure, or chemical reactions.

Magma itself is not a type of rock, but rather the molten material from which igneous rocks are formed.