Sand sculpture by a puffer fish

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...

Underwater cameras showed that the artist was a small puffer fish who, using only his flapping fin, tirelessly worked day and night to carve the circular ridges. The unlikely artist – best known in Japan as a delicacy, albeit a potentially poisonous one – even takes small shells, cracks them, and lines the inner grooves of his sculpture as if decorating his piece. Further observation revealed that this “mysterious circle” was not just there to make the ocean floor look pretty. Attracted by the grooves and ridges, female puffer fish would find their way along the dark seabed to the male puffer fish where they would mate and lay eggs in the center of the circle. In fact, the scientists observed that the more ridges the circle contained, the more likely it was that the female would mate with the male.

The lower embed shows how small the fish is in comparison to his artwork.  I've seen tiny little scooped-out nests in the sand made by freshwater fish, but never anything this elaborate.  It reminds me of the creations of bower birds.

Photos and text from Spoon and Tamago, via BoingBoing.

Reposted form 2012 to add this video of the puffer fish creating his artwork:

YouTube link.

Amazing.