A group of neat stalagmites deep in the cave at Natural Bridge Caverns. Stalagmites are calcium salts that rise from the bottom of the cave. A very similar formation called stalactites that hang down from the ceiling of the cave. They tell you to memorize this saying to remember the difference of the two: Stalactites “Hang tight” from the ceiling and Stalagmites might fall over. They both take thousands of years to form.