A worker checks the cultivation of waterweed as food for oysters in Shanxiahu Village of Shanxiahu Town, Zhuji City of east China's Zhejiang Province, Dec. 6, 2018. Pearl industry in Zhuji has upgraded its development mode from polluted water cultivation to clean water cultivation through ways such as combination cultivation of fishes and oysters, tail water treatment. There are nowadays about 4,200 Mu (about 280 hectares) of pearls cultivated in Shanxiahu Town. (Xinhua/Weng Xinyang)