'Kurma' is the second avatar of Lord Vishnu after the 'Matsya' avatar.
During the 'Samudra Manthan’, Vishnu took the form of a turtle and bore upon himself the weight of Mount Mandara, which was used as a churning rod.
Samudra Manthan was a fight between the Gods and Demons for the coveted Nectar being released by churning the Ocean of Milk. On consuming the nectar, either sides could become immortal, and reserve a place in heaven.
'Kurma' is one the interesting forms of Lord Vishnu among his ten avatars (Dashavatara).
It is a wise application of natural form to bring solution to a natural calamity.