They say that long ago, while San Teodulo, Bishop in the Valais district, was crossing the Livournea Col, after evangelising the Bionaz area, ran the risk of falling down a precipice because of a snake which had frightened his donkey.

Then the saint cursed the snake and said: "You shall never live in this place again!".

It was thanks to this curse, according to the elderly people in Bionaz, that nobody has ever seen any trails of vipers in that area from that day on. It was tradition to reach that spot, collect some soil to scatter around houses and kitchen gardens in order to keep snakes away.

They also say that the donkey, on that occasion, left its hoof-print on a rock and the shape of its lips on a bowl-shaped stone where fresh water fell.

According to the tradition the first rock is known as Pas de l'âno, the latter as Pot de l'âno.