https://en.wikipedia.org/wiki/Samudra_manthan
Devas formed an alliance with asuras to jointly churn the ocean for the nectar of immortality and to share it among them.
The churning of the Ocean of Milk was an elaborate process. Mount Mandara was used as the churning rod, and Vasuki, the king of serpents, who abides on Shiva's neck, became the churning rope.
The gods and demons pulled back and forth on the snake's body alternately, causing the mountain to rotate, which in turn churned the ocean. However, once the mountain was placed on the ocean, it began to sink. Vishnu, in the form of the turtle Kurma, came to their rescue and supported the mountain on his back.
https://en.wikipedia.org/wiki/World_Turtle
https://en.wikipedia.org/wiki/Chronos
Chronos is a god, serpentine shape in form, with three heads—those of a man, a bull, and a lion.[citation needed] He and his consort, serpentine Ananke (Inevitability), circled the primal world egg in their coils and split it apart to form the ordered universe of earth, sea and sky.