That's how I was taught to remember that stalactites are the ones that come down from the ceiling, and stalacmites are the ones that come up from the floor.  Why does this matter you ask?  Because you'll look really smart knowing that on the glow worm caves of Waitomo tour.

While the tour is worth doing if you're in the area, I will say that I wasn't floored by it.  One problem is that you're in a group of 50 people.  The other is that the actual glow worm area is really small.  Since it's pitch black it took me a few minutes to realize the boat was just going in circles and we were looking at the same patch of ceiling the whole time.

Excuse the stolen photo from the website, but apparently it's a "sacred" place so we couldn't take pictures.  I guess exceptions can be made for advertising materials.