Cave formations, such as stalagmites and stalactites, are formed over long periods of time by the deposition of minerals from water dripping through the cave ceiling or walls. Stalagmites are formed when the water droplets fall to the floor and leave behind a mineral deposit that slowly builds up over time. Stalactites are formed when the water droplets drip from the ceiling and leave behind a mineral deposit that slowly builds up over time. Both of these formations are important features of many caves and can be found in many different shapes and sizes.