Osprey Reef Osprey Reef Osprey Reef is a submerged atoll in the Coral Sea, northeast of Queensland, Australia. It is part of the Northwestern Group of the Coral Sea Islands. Osprey Reef is roughly oval in shape, measuring , and covers around . It has a perimeter of . The central lagoon is only deep. The reef sits atop a seamount in deep water. It is an isolated location some from other reefs. The almost vertical reef walls, which rise from a depth of about , are home to a dwarf form of "Nautilus pompilius" that is isolated from other nautilus populations
Coral reef approximately 20,000-year-old Great Barrier Reef offers an example of how coral reefs formed on continental shelves. Sea level was then lower than in the 21st century. As sea level rose, the water and the corals encroached on what had been hills of the Australian coastal plain. By 13,000 years ago, sea level had risen to lower than at present, and many hills of the coastal plains had become continental islands. As sea level rise continued, water topped most of the continental islands. The corals could then overgrow the hills, forming cays and reefs. Sea level on the Great Barrier Reef