These mysterious underwater crop circles are about 7 feet wide and are made on the seafloor off Japan for the single purpose of attracting mates.
Females lay eggs in the center of the circles, and then the males fertilizing them externally.
These new geometric patterns have three features never seen before.
- They involve radially aligned ridges and valleys outside the nest site.
- The male decorates these ridges with fragments of shells.
- The male gathers fine sediments to give the resulting design a distinctive look and coloring.
It takes about seven to nine days for the pufferfish to construct the circles.