While diving 80 ft below the sea level Japanese photographer Yoji Ookata discovered a mysterious 6.5 ft wide circle intricately carved from sand. For its resemblance to crop circles, Ookata named his new finding a “mystery circle,” and decided to bring a whole TV crew to try solve the mystery.

The footage revealed that the mysterious circle was carved by a tiny fish who skillfully work with its single fin. It turns out that this is the way the female fish attract the opposite sex. Later the couple uses the center of the circle to lay the eggs, as the sand riffles serve as a protection against currents.

It is estimated that only 5% of the oceans have been explored so far. Just try and imagine, what could be hidden in the remaining 95%…

Sources: ookatayouji.amaminchu.comcgi2.nhk.or.jp, spoon-tamago.com