KURMA AVATAR: This is the incarnation assumed by Lord Vishnu in the form of a tortoise. Vishnu incarnates himself as a tortoise which forms the base of the Mandara mountain when the ocean of milk (ksheera-sagar) is churned by the Gods and demons to extract the nectar of immortality. During the churning of the ocean of milk, the churning rod which is the Mandara mountain which becomes very unstable. Vishnu assumes the form of a tortoise to form the base of the Mandara mountain giving it stability.
This print from the Ravi Varma Press derived from a painting by Raja Ravi Varma depicts Kurma Avatar as a human with the lower part of his body as a tortoise. He has four hands and carries the mace (gadha) and lotus (padma) in his normal hands and the conch (shank) and discus (chakra) in his ancillary hands.