A rock that forms from other rocks due to heat and pressure beneath the Earth's surface is known as a metamorphic rock. Metamorphic rocks are formed through a process called metamorphism, where existing rocks undergo physical and chemical changes due to intense heat and pressure within the Earth's crust.

As the original rocks, known as protoliths, are subjected to these high temperatures and pressures, their original mineral composition, texture, and structure are transformed. The protoliths may be sedimentary, igneous, or even pre-existing metamorphic rocks.

During metamorphism, the minerals within the rocks recrystallize, forming new minerals or rearranging the existing ones. These changes can result in the formation of distinct foliations or banding in the rock, where platy minerals like mica align and create layered structures. The recrystallization process also enhances the density and hardness of the rock, making it more resistant to weathering and erosion.

Examples of common metamorphic rocks include slate, which forms from the metamorphosis of shale; marble, which is derived from limestone; and quartzite, which results from the transformation of sandstone. Each type of metamorphic rock is characterized by its unique mineral assemblage and texture, reflecting the specific conditions and intensity of the heat and pressure involved in its formation.