Just like tree rings, a secret reef discovered behind the world's largest reef system can provide valuable insight on Australia's oceanographic history.

As reported by Tech Times, researchers from several universities in Australia have discovered that the Great Barrier Reef is actually much more massive than previously thought.

With the help of the Royal Australian Navy, experts from Queensland University of Technology, James Cook University and University of Sydney uncovered another massive reef with strange mounds behind the iconic barrier reef system.

Because of the shape of the mounds, scientists are now referring to it as a secret "doughnut" reef.

Like Tree Rings

Tree ring patterns are often analyzed and dated so experts can determine the growth of a tree, when the tree was formed and the kind of environment it was formed in. Additionally, these rings can also indicate the temperature, cloudiness and moisture, researchers say.

Applying the same logic, the strange mounds found in the doughnut reef can also help scientists unravel the mystery behind the past climate on the Great Barrier Reef.

In fact, the sediment gives experts the opportunity to study changes in the seafloor over the last 10,000 years, as well as the impact of increasing acidification and water temperatures.

Marine geologist Robin Beaman from James Cook University says the geological structures are about 20 meters (65 feet) thick, and can tell scientists a lot about oceanographic history.

Interestingly, the doughnut reef is made up of bioherms, which are circular mounds of green algae known as Halimeda. This green algae calcifies as it dies and forms limestone flakes that pile up over the years.

Over the last 10,000 years, the green algae produced a vast reef that encompasses 6,094 square kilometers (2,353 square miles) that stretch from the Torres Strait to Port Douglas.

This meant that the reef is actually three times bigger than the previously estimated size.

Mardi McNeil, lead author of the paper, says the bioherms are sometimes like singular circular rings and sometimes clustered in groups of three or four.

With the shallowest structure situated at 20 to 50 meters (65 to 164 feet) deep, very few people have seen the newly discovered reef before, says McNeil.

Beaman says experts have known about the geological structures in the Great Barrier Reef since the 1970s, but the true nature of the size, shape and scale have never been revealed until now.

"What we found deep behind the Great Barrier Reef has amazed us," says Beaman.

Meanwhile, scientists say there still lies the question of what lives on the newly discovered reef today. Because of its depth, it could either have lush veneer of living green or just white limestone flakes, added McNeil.

Photo: Steve Parish/Lock the Gate Alliance | Flickr