As the water drops from the stalactite down to the stalagmite, the minerals in the water collect to create rock formations. Stalactites hang from the ceiling and are created by water dripping from the roof of the cave. Stalagmites grow up from the ground and are created as water from the roof of the cave hits the ground. In each case, minerals are deposited either hanging from the roof of the cave (stalactites) or on the ground (stalagmites).