Settings: Formula 51, Render 5, Color modified 24-3, Transform Arctan, Inside-Out, Julia Mode, Iterations 10.

The Orbit Counting render settings (2-5) can make some surprising images. This one uses the color menu selection number 24 which is not one I use alot. I've found 13 to be the best choice in most cases, but some formulas and render combinations seem suited to others.