Story highlights Discovery of a large field of unusual circular mounds announced Friday

Unique-looking structures are created by a green algae, scientists say

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(CNN) Australia's famed Great Barrier Reef may be in trouble -- but it's not all bad news coming out of the region.

Scientists have discovered a large doughnut-shaped coral reef in northern Queensland, sitting behind the iconic Great Barrier Reef.

The discovery of a large field of unusual circular mounds was announced Friday by a group of scientists from James Cook University, University of Sydney and Queensland University of Technology, who worked with laser data from the Australian Royal Navy.

Mardi McNeil from Queensland University of Technology and lead author on the new research paper called the discovery "vast."

"We've now mapped over 6,000 square kilometers (about 2,300 square miles)," McNeil said. "That's three times the previously estimated size, spanning from the Torres Strait to just north of Port Douglas."