Why does water expand when it freezes? What would be the consequences to life on Earth if it did not?

Question

Why does water expand when it freezes? What would be the consequences to life on Earth if it did not?

Answer 1

 awright fools. Its all about the chemistry. It has to do with the bonding between hydrogen and oxygen.  It would change life as we know it. Life would not be possible. We would never have existed. But it is pointless to think about because water does expand when frozen. So suck it!