Ice alga

Ice algae is any of the various types of algal communities encountered in annual and multi-year sea-ice. The ice algal communities play an important role in primary production and are therefore considered an important part of both Polar ecosystems.
Sea-ice algal communities can be found between ice crystals or attached to them, in the interstitial water or brine channels between ice crystals, or simply associated with the undersurface of the ice.