Water Droplet in a Cave
Cave formations depend on water flowing through the limestone that makes up the cave walls. As the water passes through, it dissolves the limestone. Then, the calcium recombines with carbon dioxide in the water to create calcium carbonate.
The calcium carbonate precipitates out of the water as the water evaporates or flows away, building up over time into cave formations.
Formations created by dripping water are known as dripstone formations. Well-known speleothems like stalagtites and stalactites are dripstone formations.