Limestone

rocks · fossils · ocean · chemistry

Made from shells and coral. Limestone forms when the shells and skeletons of sea creatures pile up on the ocean floor over millions of years. As layers build up, they get pressed and cemented together into solid rock.

Crystal forms of calcium. Limestone is made of two minerals called calcite and aragonite, which are both forms of calcium carbonate. This is the same stuff that makes seashells hard and sparkly.

Time capsule of fossils. Limestone often contains fossils of ancient animals and plants, which help scientists understand what life was like millions of years ago. These fossils tell us about creatures that lived in ancient oceans and how life has changed over time.

Comes from water. Limestone forms when calcium-rich minerals precipitate out of seawater, either when creatures build shells or through chemical processes. This can happen both with the help of living things and without them.

Useful building material. Limestone is the main source of lime, a material used in cement, concrete, and mortar. This makes limestone super important for building houses, roads, and other structures.