For 250 million years, corals have been a beautiful undersea landscape - they cover less than two-thousandths of the ocean floor but provide a home to nearly 30 percent of all marine fish. But coral reefs have been declining for the past 20 to 30 years due to global warming. To restore the vast stretches of corals under the sea, Chinese coral biologist Huang Hui has devoted half her life to the seabed restoration of the South China Sea. Huang and her team first breed "coral seedlings" in a nursery, and then transplant them to the seabed. Growing corals on the seafloor is no easy job.