Turtle
(see also animals)

A great deal of mythology exists in regard to the turtle. In the Far East, the shell was a symbol of heaven, and the square underside was a symbol of earth. The turtle was an animal whose magic could help you unite heaven and earth within your own life. A symbol of the turtle was an invitation for the blessings of both heaven and earth.

The turtle is a shore creature, using the land and the water. All shore areas are associated with doorways to the Faerie Realm. The turtle is sometimes known as the keeper to the doors. Turtles thus were often seen as signs of fairy contact and the promise of fairy rewards. 
From: Owl's Rest

. . . the turtle was a symbol of the female sex organs and sexuality.  To the Native Americans, it was associated with the lunar cycle, menstruation, and the power of the female energies.  The markings and sections on some turtles total thirteen.   In the lunar calendar, there are either thirteen full moons or thirteen new moons alternating each year.  Many believe this is where the association with the female energies originated.  Turtle is the symbol of the primal mother. From Animal-Speak by Ted Andrews, Llewellyn Publications, 1997.)

Songs referenced: 

Space Dog