It was the structure of DNA. Watson and Crick stole the credit from a woman whose name I can't remember, but basically she took really long exposure photographs (24 hours for some) and saw an X shape, which was the corresponding sign of a double helix. It was a pretty complicated method she was using and nobody had thought of using it for DNA research until then.
Answer:
Great Barrier Reef
Explanation:
Location
Coral Sea, Queensland, Australia
The largest in the world
Stretching for 1,429 miles over an area of approximately 133,000 square miles , the Great Barrier Reef is the largest coral reef system in the world.
