(ECNS)-- Craspedacusta sowerbyi, an almost-extinct freshwater jellyfish, appeared in a well in Wuzhishan, S China's Hainan in early July.
They are about 20-25 mm (approximately 1 in) in length.
They only survive in unpolluted water and a temperature below 35 ℃.
With a reputation of "living fossils", the species is believed to have been living on earth for 1.5 bln years.
