Osiris dick was swallowed by a crock when Set chopped him up. When Isis put Osiris back together the dick could not be found - so she fashioned a new one of gold.
Set learned of his brother's return and went out to find his body. He managed to get Nephthys to tell him where it was, and when he found it, he hacked it into pieces and scattered it across the land and into the Nile. When Isis returned, she was horrified but quickly composed herself and went to work finding the pieces of her murdered husband. With Nephthys' help, she recovered all of the body parts except the penis, which had been thrown into the Nile and eaten by the oxyrhyncus fish, which is why this fish was forbidden food in ancient Egypt.
