James Cook University, University of Sydney, and Queensland University of Technology scientists working with laser data from the Royal Australian Navy have discovered a vast reef behind the familiar Great Barrier Reef. JCU’s Dr Robin Beaman says the high-resolution seafloor data provided by LiDAR-equipped aircraft have revealed great fields of unusual donut-shaped circular mounds, each 200-300 meters across and up to 10 meters deep at the center. Halimeda is a green macroalgae composed of calcified leaf-like segments.  As these plants die, these segments turn white and accumulate over thousands of years forming thick mounds called bioherms.  Where these plants have died, A living layer of Halimeda algae covers the bioherms and stretches across an area of 6095 km2 on the landward side of the reef. MORE