A spiral which has the following property: If you start heading towards the center, the distance between successive lines decreases in a fixed proportion. Snail shells display a logarithmic spiral, as do patterns of sunflower seeds and pine cone kernels. You can plot the rectangular outline of a logarithmic spiral on a cartesian plane using the fibonacci numbers in the following manner: Start at (0,0), plot a point. Move right by the next fibonacci number (1). Plot a point. Move up by the next one (also 1), plot a point. Then left, then down, then repeat!