'Serpent' in the Bible

"When Pharaoh speaks to you, saying, 'Perform a miracle!' then you shall tell Aaron, 'Take your rod, and cast it down before Pharaoh, that it become a serpent.'"

Moses and Aaron went in to Pharaoh, and they did so, as Yahweh had commanded: and Aaron cast down his rod before Pharaoh and before his servants, and it became a serpent.

Go to Pharaoh in the morning. Behold, he goes out to the water; and you shall stand by the river's bank to meet him; and the rod which was turned to a serpent you shall take in your hand.