Here's why:

* Limestone: Primarily composed of calcium carbonate (CaCO3).

* Metamorphism: The process of changing the texture and mineral composition of a rock under heat and pressure.

* Marble: Formed when limestone is recrystallized under heat and pressure. The original calcite crystals in limestone are rearranged into larger, interlocking crystals, giving marble its characteristic coarse-grained texture.

While marble is the most common result, other metamorphic rocks can also be formed from limestone depending on the specific conditions of metamorphism:

* Skarn: Formed when limestone reacts with silica-rich fluids.

* Calc-silicate rocks: A variety of rocks formed when limestone reacts with other minerals under high pressure.