The Totem of Nehual is something of a Maltese Falcon. Many have spent long periods of their life searching for it, spending vast sums of money, and in the end never finding it, or only finding it long enough to lose it.
With regard to the plot "Sleeping Mines of Elathon":
You manage to get the water wheel in the mine working which operates a pump to clear the flooded lower levels. As you explore the dank tunnels of the lower galleries, you can hear the creaking of the wheel above. You enter a low-ceilinged passage and are crawling on your backs, when the creaking stops. The water starts seeping wetly around the back of your head...