devonian corals

devonian corals fossils Thedford, Ontario These are the fossilized skeletons of tiny animals (Heliophyllum halli) that lived over 360 million years ago. As corals grow, they secrete thin layers of calcium carbonate on their skeleton. This leaves ridges that mark annual growth and finer lines that record monthly and daily growth. Studying these lines, we discover that the Devonian year was 400 days long and divided into 13 lunar months.