A "fish nest"

Third Place, Conservation Hope. A male white-spotted pufferfish creates an intricate spawning nest in the sand. The fish carefully shapes a two-meter-wide radial pattern using only his fins. Built over several days, this structure and its subtle details reveal the extraordinary effort this small fish invests in reproduction.

This was one of the winning photographs in the Ocean Photographer of the Year competition, from a gallery in The Atlantic.  Photo credit Yuta Shigeno,