CaCO3, besides being known as limestone, can also be referred to as:

* Calcium carbonate (its chemical name)

* Calcite (a mineral form of calcium carbonate)

* Marble (a metamorphic rock formed from limestone)

* Chalk (a soft, white, porous form of limestone)

* Travertine (a banded form of calcium carbonate deposited by hot springs)

These are just a few of the many names for CaCO3, depending on its specific form and origin.