But even for a man who spent the last 50 years immersed in the underwater world of sea life, the ocean proved infinitely mysterious. While diving in the semi-tropical region of Amami Oshima, roughly 80 ft below sea level, Ookata spotted something he had never seen. And as it turned out, no one else had seen it before either.
On the seabed a geometric, circular structure measuring roughly 6.5 ft in diameter had been precisely carved from sand. It consisted of multiple ridges, symmetrically jutting out from the center, and appeared to be the work of an underwater artist, carefully working with tools. For its resemblance to crop circles, Ookata dubbed his new finding a “mystery circle,” and enlisted some colleagues at NHKto help him investigate.
( via spoon-tamago.com)