Monster Sunfish off the San Diego coast. Photo by Daniel Botelho

How crazy is this fish? Daniel Botelho, a photographer who specializes in underwater photography, in 2010 shot this photo of a sunfish, also known as a Mola Mola, off the coast of San Diego.

The world’s heaviest boned fish, these guys can reach 10 feet long and 5,000 pounds. After the picture became a Facebook hit, National Geographic interviewed Dr. Tierney Thys, a Sunfish expert, about these gentle giants.

“Their design has evolved to be more like an armored tank with a stiff body as opposed to a streamlined torpedo body like other fish,” he said. “They just look like big puffer fish on steroids.”