I will take away all your beauty, and you will be an ugly monster forever!!!
You get to stay here forever!!!
Athena told Medusa that beauty is only temporary in mortals. It does not help with problems. As a punishment, and to teach everyone else a lesson, Athen turned her into a monster. She now has living green snakes for hair. The fight and squirm on top of her head.
Medusa was now an ugly creature. Just by looking at her, you could be turned to stone. She was sent off to the ends of the earth. There she would live with her gorgon sisters, unable to hurt anyone.