This model maps turtles between cartesian and spherical 3-dimensional coordinates. To create a sphere the program randomly generates turtles about the shell of a sphere in spherical coordinates. To render the sphere in the StarLogoT graphics window it translates the turtles from spherical to cartesian coordinates.
For detailed instructions on using the program, take a look at the info window from the Sphere model.
Click on one of the pictures to see a quicktime movie of the model: