During the summer three years ago, Keiichi Matsuura dived into the seas off Amami-Oshima island in Kagoshima Prefecture. On the seabed about 25 meters under water, he saw a round-shaped geometric pattern about two meters in diameter on the pure white sand.
Local residents called the pattern a "mystery circle." The artists under the sea were later found to be a new species of small fugu about 10 centimeters long. The body of the puffer fish is faintly golden-coloured with many white star-shaped spots.
Matsuura, a 66-year-old ichthyologist, said he was surprised because "if they were humans, [making such patterns] is equivalent to drawing a circle 30 meters in diameter freehand."
He is an ichthyologist at the National Museum of Nature and Science. He has worked as an ichthyologist for 40 years.
When he was asked to examine the mystery circle, he felt in his bones that he was dealing with a new fish species.
"Though I have found more than 20 new species of fish, I had never seen a fish that creates such a complicated pattern as a nest," he said.
Matsuura examined the bodies of the fish, such as the distribution of spines. Last year, he named the species "Amami hoshizora fugu" in Japanese and reported his finding to a journal of an academic society.
The fish species was chosen as one of the world's top 10 newly found species by an international research organisation.
He said he came up with the name of the new species because, "I wanted to express local people's passionate feelings of carefully watching the fugu."
Males draw the geometric pattern, and females, attracted by them, lay eggs in the centre of the circles. However, it is still a mystery why their nests need to be that shape.
"The sea always provides something new. In the future, I'm looking forward to encountering creatures that are beyond my imagination," Matsuura said, showing his unchanged affection toward the sea.