There was a Gandharv (divine musician of heaven) in the court of Indra whose name was Cronch. He was the main gandharv who loved his music more than anything. Sometimes he used to dive in the music so much that he forget the nearby situations.
Curse of Vaamdev
Once Rishi Vaamdev came in the court of Indra to discuss something very important. At that time Cronch was playing music and everybody was enjoying it.
Vaamdev started talking but Cronch didn’t stop playing. He then warned Cronch about his important issue and asked him to stop for some time. Cronch was arrogant and he asked what issue could be more important than the music?
Vaamdev got furious over his talk back but tried to make him understand. When Cronch finally didn’t listen, Vaamdev cursed him to become a rat.
He immediately turned into a giant rat and started running all over the heaven. Indra asked the way of redemption on his behalf then Vaamdev gave him direction through which he could get a good position.
Cronch Became Mount of Ganesha
From the directions of Vaamdev, Cronch left heaven and went to a village. People got terrified looking at the giant rat. He started destroying food items and disturbing people.
When Ganesha got the news of giant rat, he went to see it. People asked help from Ganesha and He captured the rat.
Ganesha brought the rat in Kailash and asked Shiva to punish him for his sins. Shiva being Pashupatinath, always gives chances to everybody so that they can improve. He asked Ganesha to deal with the rat and punish him the way he want.
Ganesha is kind and soft heart. He punished the rat in a very different way by making him his mount. Rat turned into Cronch and thanked Ganesha for making his life worthy.