This would be a hell of a thing to come across on the ocean floor. What is it? A crop circle made by confused aliens? Tire treads from an undersea rover doing wheelies? The print of a massive octopus wearing fashionable shoes? A MANHOLE?
As it turns out, the designs are pufferfish sex palaces. Photographer Yoji Ookata discovered that male pufferfish rake the Zen-garden designs into the sand with their fins, for the purpose of wooing females, who apparently have a well-developed aesthetic sense — the more complex the structure, the more likely they are to mate. The fish then lay eggs in the center of the circle, where the ridges protect them from ocean currents.
Oh, egotistical humans. Did you really think you were the only species that could create sculpture gardens on the ocean floor? As if. Pufferfish are way better at underwater stuff than you are.