What type of rock forms from an existing rock that is changed by heat, pressure, or chemical reactions?

Metamorphic rock is formed from pre-existing rocks that undergo significant changes due to heat, pressure, or chemical reactions over time. This process, known as metamorphism, can alter the physical and chemical properties of the original rock. For example, shale, a sedimentary rock, can be transformed into slate when subjected to increased pressure and temperature. The unique characteristic of metamorphic rocks is that they retain some features of their original rock, such as minerals or texture, while also displaying new attributes that arise from the transformational processes. This distinction makes metamorphic rock essential for understanding the dynamic nature of Earth's geology.