Often a drop of water that seep into the cave, contain particles of limestone or other minerals. A drop of water falls, and the fine particles of minerals remain on the ceiling of the cave. A fallen drop should be a new and so on... many years later on the ceiling of the cave stalactite grows - stone icicle. And on the floor, where from a stalactite dripping water, it forms a stalagmite. Through thousands of years, the stalactite and a stalagmite join and turn into the column.