You wouldn't expect to learn much about the properties of water by watching a square dance. But think again. Following the caller's lead, the dancers meet, separate, weave, and swing in a perfectly fluid manner.
It turns out that similar coordinated maneuvers—with water molecules taking the places of the dancers—may be responsible for some of water's most puzzling features, an array of recent research findings suggest.
As liquids go, water is a radical nonconformist—differing from other liquids in dozens of ways (see the latest count at www.lsbu.ac.uk/water/anmlies). Most famous among water's peculiarities is its density at low temperatures. While other liquids contract and get denser as they cool toward their freezing points, water stops contracting and starts to expand. That's why ice floats and frozen pipes burst.
http://www.sciencenews.org/articles/20080126/bob9.asp