Here's why:

* Stalactites hang down from the ceiling of a cave. They are formed by dripping water that carries dissolved minerals. As the water evaporates, it leaves behind mineral deposits, which gradually build up over time, forming the icicle-like shape.

* Stalagmites grow upwards from the cave floor. These are formed by the dripping water that falls from the stalactite, depositing minerals on the floor.

So, to be accurate, stalactites grow down from the ceiling, not up from the floor.