30 years ago, Peter Ward discovered and identified Allonautilus scrobiculatus, which was a new species of nautilus at the time; but until recently he had never seen it again.

According to NBC News, the nautilus is defined by its gooey shell with a hairy coating that wards off predators by making it impossible for them to grip. Ward, a biologist at the University of Washington, detailed his recent reunion with the rare underwater mollusk.

A cousin to cuttlefish and squid, the nautilus is sometimes described as a "living fossil" because it has remained the same over millions of years while also outliving other members of its subclass.

"Before this, two humans had seen Allonautilus scrobiculatus," Ward said in a news release. "My colleague Bruce Saunders from Bryn Mawr College found Allonautilus first, and I saw them a few weeks later.

"Some features of the nautilus - like the shell giving it the 'living fossil' label - may not have changed for a long time, but other parts have."

Ward and his fellow researchers returned to Papua New Guinea to observe the nautilus species, but knew they would have to expertly lure out the expert scavengers. To make the observations, Ward and his team set out bait and cameras to capture the nautiluses.

"We started using this approach in 2011," he said in the release. "This year, there were about 30 guys involved and each day we would all watch the movies from the night before at 8X speed. There were a lot of 'ohs' and 'ahs'.

"For the next two hours, the sunfish just kept whacking them with its tail."