When a sedimentary rock undergoes great amounts of heat and pressure, it turns into metamorphic rock.

Here's why:

* Sedimentary rocks are formed from the accumulation and cementation of sediments like sand, silt, or organic matter.

* Metamorphic rocks are formed when existing rocks (igneous, sedimentary, or even other metamorphic rocks) are transformed by heat and pressure deep within the Earth's crust. These conditions change the mineral composition and texture of the rock.

Think of it like baking a cake. The raw ingredients (sediments) are transformed by heat (pressure) into a completely new, more complex product (metamorphic rock).