Brinicle

Underwater icicles, ice tubes, which resemble stalactites, reaching down from the sea ice to the bottom of the sea. Brinicles are present in very cold oceanic water with normal salinity, mostly in the Arctic and Antarctic.

When sea ice is formed, substances dissolved in water do not enter the ice crystals’ structure, thus increasing locally salinity. This brine can form streams, flowing downwards towards the ocean bottom. Brine has lower temperature, than the surrounding water, so a thin layer of ice can form on the surface of the stream, thus building a pipe. If a brine stream reaches bottom it can cause freezing of the near-bottom water and death of bentonic organisms.