Stalactite

A stalactite ( /ˈstæləktaɪt/, /stəˈlæktaɪt/; from the Greek stalasso, (σταλάσσω), "to drip", and meaning "that which drips") is a type of speleothem (secondary mineral) that hangs from the ceiling of limestone caves. It is a type of dripstone. The corresponding formation on the floor of the cave is known as a stalagmite.