A team of researchers from University of Nebraska-Lincoln has predicted a new molecular form of ice with a record-low density. The proposed ice would be about 25 percent less dense than a record-low form synthesized by a European team in 2014. If the ice can be synthesized, it would become the 18th known crystalline form of water and the first discovered in the United States since before World War II.
https://www.sciencedaily.com/releases/2016/02/160212200227.htm
https://www.sciencedaily.com/releases/2016/02/160212200227.htm