Limestone formations are geological structures primarily composed of the mineral calcite, which is derived from the remains of marine organisms like corals and shellfish. These formations often develop in shallow, warm ocean waters, where the accumulation of organic material and sediment over millions of years leads to the creation of limestone rock. Limestone can be found in various forms, including stalactites and stalagmites in caves, as well as large cliffs and plateaus. It is commonly used in construction and industry, serving as a key ingredient in products like cement and lime.