The result of this process is that ice (in its most common form) floats on liquid water, which is an important feature in Earth's biosphere.
It has been argued that without this property, natural bodies of water would freeze, in some cases permanently, from the bottom up,resulting in a loss of bottom-dependent animal and plant life in fresh and sea water. Sufficiently thin ice sheets allow light to pass through while protecting the underside from short-term weather extremes such as wind chill.
This creates a sheltered environment for bacterial and algal colonies.
When sea water freezes, the ice is riddled with brine-filled channels which sustain sympagic organisms such as bacteria, algae, copepods and annelids, which in turn provide food for animals such as krill and specialised fish like the bald notothen, fed upon in turn by larger animals such as emperor penguins and minke whales.