635 million years ago, the Earth went through a harsh ice age that scientists thought for an eternity covered it completely until it turned it into a ball of snow. Scientists agree that this period saw the largest accumulation of ice in the history of the Earth, but it may not have been a complete sphere.
New evidence collected in the eastern Xinongjia forest area of China's Hubei province suggests that the land was not completely frozen, but there were patches of open water in some shallow seas in mid-latitudes.