What's the Purpose of the Opening of the Mouth Ceremony?

The opening of the mouth ceremony was crucial, and you can see a wonderful depiction of it in two thank common stone. The purpose was that the pharaoh I in this scene is taking a little tool called an ad that's a farming tool. And he touches it to the mouth of the deceased and he says, "You young again you live again" Okay, anything else we should know about mummification? No, I'm sure little boys will think of other questions but that're that's that's mummies.