Medusa was turned into a Gorgon by reason of either two things:
1. Medusa and Poseidon were caught together at Athena's temple, and since Athena was promised to Poseidon, Athena could not punish him, so she punished Medusa by changing her into a monster.
or
2. Medusa was a normal human woman that worked in the temple of Athena. Medusa thought herself to be more beautiful than any goddess, even Athena. When Athena found out about this, she turned Medusa into a monster that no one would want to look at.
One attribute of Medusa's curse was to have eyes that turned anything into stone once they were looked into. Just a fraction of a look was enough. Just to show that no one would ever look upon her in beauty again.
Perseus, the killer of Medusa, used a shield to look upon the reflection of Medusa, since a reflection will not harm you.
As a side note, there is some evidence that the myth is based around the real illness, Seefer's disease (a.k.a. Human Statue Syndrome), which causes one's skin to harden in roughly twenty minutes (this being said, there have only been a handful of cases known to modern medicine).
actually it is only if you look at her in person which would be imposable because thousands of years ago Perseus killed her by cutting of her head and then using her head as a weapon
[Because of a curse Athena casted ] Medusa was SO ugly , when you look into her eyes you will turn to stone
if you look at her you die
Medusa is a mythical creature that can turn anyone to stone if you look into her eyes. Even when the head to severed it is still capable of turn you to stone. In that case, Percy must carefully wrap the head without looking into her eyes.
She is able to turn people to stone and is beautiful
turn people to stone
you turn into stone
Because even severs she can still turn him into stone if he looks into her eyes
You would turn into stone (so rock) when you look into Medusa's eyes.
If you look him in the eyes, you'll turn to stone.
You turn to stone hope this helped
you would turn to stone
Any living organism that looks at her will turn to stone.
When someone looks at Medusa they turn in to stone.