Limestone Formations inside a Cavern

Many stalactites start as soda straws, hollow tubes of calcite about as wide as a drop of water. Each drop leaves a thin ring of mineral at the tip before it falls. Once the tube clogs, the water runs down the outside instead and the straw slowly thickens into a cone. In this cave jigsaw puzzle the ceiling bristles with them, while stalagmites rise from a wet floor and a huge fluted column joins the two. The passage beyond fades off into the dark.