Stalactites drip from the ceiling in a cave in the Dordogne region of France. These rock formations form when mineral-laden water drips through the cave, leaving behind calcium carbonate or other minerals. Water that falls onto the ground below from the growing stalactite can form stalagmites. When these ground formations meet up with the ceiling formations, the result is a "column."
The Kaklik cave in Turkey is fed by sulphur-filled waters, which create these white formations not unlike those seen at Mammoth Springs in Yellowstone National Park. The water's sulphur content gives these caves a stinky rotten-egg smell.