Here's why:

* Metamorphic rocks are formed when existing rocks (igneous, sedimentary, or even other metamorphic rocks) are transformed by heat, pressure, and/or chemically active fluids.

* Phyllite is a foliated metamorphic rock, meaning it has a layered or banded appearance due to the alignment of minerals during the metamorphic process.

* Phyllite forms from the metamorphism of shale (a sedimentary rock).

Let me know if you have any other questions about rocks!