I'm fascinated by the designs in nature such as the star shape at the center of this species of fire urchin. This image is a closeup of the same variety found in the image Large Fire Urchin. See Fire Urchin Shrimp for a tiny critter found on a similar urchin. For the oblong version of this image link to Fire Urchin Close
This image is available in standard and square formats. The maximum sizes are 6 x 9 and 5 x 5 respectively.