Water Is one of the few compounds whose solid phase floats on it's liquid one.
Most chemicals by far become denser as they get colder. Water does this too except near its freezing point. Its solid crystal structure requires more space that its freely moving liquid phase. This peoperty is a function of water's strong hydrogen bonding which no other chemical matches as far as I remember. You won't find methane icebergs on a methane see. Methane icebergs on an ethane sea (don't know their densities) or some other mismatch possibly, but not an organic solid on its own liquid phase.
Regards,
Mark