..and the only substance which increases in volume when it freezes.
my 0.02$
Yeah, water is pretty amazing stuff. Without it, life as we know it wouldn't exist. And the probability of it existing in liquid form is very remote. Earth is indeed a privileged planet.
.and the only substance which increases in volume when it freezes.
I know one other that increases in volume when hardened.
and the only substance which increases in volume when it freezes.
Not quite. Several metal alloys do that--notably typemetal, an alloy of antimony, bismuth, and lead. This was vital for filling all the tiny crevices in type molds (linotype machines). An alloy that shrunk as it solidified would be very poor for printing.