SALT LAKE CITY – It was first thought to be a giant piece of driftwood that had been pushed to shore, but as witnesses got closer, they realized they weren’t looking at driftwood at all, but a 6-foot-long ocean sunfish.

The specimen was first spotted by a group of fisherman driving on the beach in Coorong National Park, Australia, according to the BBC.

Linette Grzelak, who posted pictures of the fish on her Facebook page, told the BBC, “I didn’t think it was real until I Googled sunfish.”

According to Grzelak, her partner Steven Jones and his friends knew what the fish was when they found it but had never seen one in real life, which is why they took pictures of it.

“He said it was extremely heavy and the skin was rough and leathery like a rhinoceros,” Grzelak said.

Our Park of the Month at Coorong National Park served up an unusual surprise for two fishers on the weekend – a sunfish... Posted by National Parks South Australia on Tuesday, March 19, 2019

According to National Parks South Australia, who reposted Grzelak’s photos Tuesday, sunfish are the world’s largest bony fish and can weigh more than a car.

Ocean sunfish, also known as mola mola, are not exactly rare, but they’re constantly mobile and don’t stay in the same spot for long, according to the South Australian Museum. The one Jones captured in the photos is actually on the small side for the species, according to the museum.

The BBC reported that this species of fish can grow over 13 feet tall and weigh more than 2.75 tons. They’re harmless to people but are often mistaken for sharks when they swim near shore, according to the South Australian Museum.

The museum’s fish collection manager Ralph Foster told CNN that the fish is called a sunfish because it enjoys basking in the sun. Because of their size and love for the sun, they can easily be hit by boats, and some could actually sink yachts, according to Foster.

"We know very little about them. It's only in the last few years that technology has allowed us to start learning about them," Foster added.

The museum does not know the reason why this particular sunfish washed to shore.