Numbers 21 also contains a story about a snake on a pole-- God sent venomous snakes to punish the Israelites for complaining about everything, but relented when they repented. God instructed Moses to make a snake out of bronze and put it up on a pole, and those who were bitten could look at it and live.
Later in the Bible (2 Kings) it is mentioned that the people had saved the snake, named it Nehushtan* and were burning incense to it. King Hezekiah put a stop to that by breaking the snake into pieces.

*according to the footnote, Nehushtan sounds like the Hebrew for bronze and snake and unclean thing.