The slender conical speleothem that grows from water dripping from the ceiling of a cavern is a stalactite.

Here's why:

* Stalactites hang from the ceiling, like icicles. They form as water drips from the ceiling, leaving behind dissolved minerals that crystallize.

* Stalagmites rise from the floor of the cave, formed by dripping water that falls from stalactites.

So, when thinking about cave formations, remember: stalactites hang tight to the ceiling, and stalagmites might reach the ceiling someday.