Something fishy

Yoji Okato is an underwater photographer. One day, he dove into the sea off southern Japan. 

He saw something odd on the seafloor. It was a circle in the sand. The center looked smooth. A pattern of ridges was piled up around the edge of the circle. He wondered what made this circle. 

for a Cause

People came up with ideas about these sea circles. Some said they were made by ocean currents. Some thought that aliens from space made the circles. The aliens had landed their UFOs on the seafloor! 

Okato didn’t think aliens were behind the circle. He wanted to solve the mystery. He teamed up with some scientists. The team returned to the place where he had seen the circle. Nothing had changed. 

Yoji Okato

sand circle



A pufferfish flaps its fins to move sand.

The team went to the same place many times. They watched. They didn’t get any clues. The mystery was still a mystery.

Mystery Solved

One day, the team saw who was making the circle. It was a small fish. It’s called a pufferfish. The fish made tiny waves by swimming back and forth. The waves made a circle. He used his fins to make ridges. When he was done, a female fish swam by. She liked the circle so much, she laid her eggs there. The circle was a nest! Mystery solved!

A pufferfish swims back and forth as it makes a sand circle.