Photo taken on July 9, 2013 shows a porcelain crab collected by China's manned submersible Jiaolong in a cold seep area in the South China Sea. The manned submersible Jiaolong dived in a cold seep area in the South China Sea, and collected a lot of seafloor samples including deep-water shrimps, corals, crabs and carbonate rock. A cold seep (sometimes called a cold vent) is an area of the ocean floor where hydrogen sulfide, methaneand other hydrocarbon-rich fluid seepage occurs. The temperature of cold seep fluid and the bottom of the sea are similar, so we call it "cold seep". Researches on cold seep are popular in the scientific community in recent decades. (Xinhua News Agency/Zhang Xudong)