High temperature and pressure cause igneous rocks to become metamorphic rocks.

Here's why:

* Igneous rocks form from the cooling and solidification of molten rock (magma or lava).

* Metamorphic rocks form when existing rocks (igneous, sedimentary, or even other metamorphic rocks) are subjected to intense heat and pressure deep within the Earth's crust. This heat and pressure cause the minerals in the original rocks to recrystallize and change their texture and sometimes even their composition.

So, while igneous rocks can be the source material for metamorphic rocks, they don't directly transform into another type of rock. The transformation is a result of the intense heat and pressure of the metamorphic process.