None of the mentioned did it. It is the puffer fish’s work of art.
Male puffer fish attracts the opposite sex by crafting this “mysterious circle”. This art piece measuring about 6.5ft in diameter is eventually going to be their love nest. According to scientist, the more ridges the circle contained, the more likely more female fishes will be attracted.
This amazing craftsmanship was discovered by a Japanese freelance underwater world photographer, in the semi-tropical region of Amami Oshima.