Some of the materials we gather from the ground come from ancient living organisms. These living organisms include bacteria, fungi, plants and animals that inhabited the planet millions years before us. Limestone is an example of such a material. They are ancient seafloors that have acquired layers upon layers of dead aquatic animals, especially their cells, or coral reefs. 


Limestone cliffs. Limestone is made from the shells of ancient marine invertebrates.

Sometimes, individual shells can still be seen embedded in limestone cliffs. These remains of ancient living organisms are called fossils. Water can erode limestone and create magnificient stalactite caverns. They are popular tourist destinations. 


Image on the left: Fossils. Image on the right: A stalactite cavern made from limestone.

Limestone can be quarried, and its chalk can be used to make concrete. Concrete is a popular building material. It is used to make buildings and roads. Many famous buildings all over the world, such as the Giza pyramids in Egypt and the Notre-Dame Cathedral in France, are made out of limestone.

Chalk can be quarried and used to make concrete, which is a popular building material in roads and buildings.