What did Moses mount on a pole so that people bitten by snakes could look and live?

Answer: A bronze snake

Moses made a bronze snake and mounted it on a pole; anyone who was bitten and looked at it would live.

“Then the LORD said to Moses, “Make a fiery serpent and mount it on a pole. When anyone who is bitten looks at it, he will live.” So Moses made a bronze snake and mounted it on a pole. If anyone who was bitten looked at the bronze snake, he would live.”— Numbers 21:8-9 (BSB)