Fact
Water is bizarre, and life depends on the bizarreness
Almost every substance contracts when it freezes. Water expands.
Hydrogen bonding forces water molecules into an open lattice as they crystallise, making ice about nine per cent less dense than liquid water. So ice floats, lakes freeze from the top down, and aquatic life survives winter beneath an insulating lid. If water behaved normally, bodies of water would freeze solid from the bottom.