Turtles seem to possess an enviable and god-like resistance to aging, and so they came to symbolize longevity. Their link to heaven and earth made them a natural for use in divination. Turtles are also symbols of immortality and are considered temporary dwelling places for souls making their way through a series of lives on the path to Nirvana.
The turtle is a creation of nature that carries its round shell over the ground, like heaven, and has a flat bottom, like earth. With a profile resembling a mountain and the turning motion of its toes, it seemed to be a depiction of heaven and earth changing constantly through the seasons.