An ancient reef formed almost 550 million years ago was found on what is now dry land in Namibia, media reported Friday.
The fossilised reef, the oldest of its kind in the world, was formed by the first creatures known to have hard shells, Xinhua cited a study conducted by researchers of the University of Edinburgh.
The study suggested that these aquatic organisms had been building reefs about 542 million years ago.
Previously, the oldest reefs on record were dated to about 530 million years ago.
The researchers said that the tiny aquatic creatures, known as Cloudina, attached themselves to fixed surfaces and to each other by producing natural cement composed of calcium carbonate, to form rigid structures.
Cloudina were tiny, filter-feeding creatures that lived on the seabed during the Ediacaran Period, which ended 541 million years ago.
Fossil evidence indicated that animals had soft bodies until the emergence of Cloudina.
The study believed that the animals may have developed the ability to build reefs to protect themselves against increased threats from predators.
Reefs also provided access to nutrient-rich currents at a time when there was growing competition for food and living space.
