A brinicle or an ice stalactite is a formation of sea ice that gets generated when extremely cold saline water is introduced in ocean water. During winter, the temperature above the sea is -20C, whereas, the temperature of the sea water is only -1.9C. Heat tends to flow from the warmer sea to the extremely cold air, resulting in the formation of ice pipes.
The salt in this freshly created ice is concentrated and then later gets pressured into the brine channels. It’s cold and salty traits; make it denser than the water beneath. It results in the sinking of brine in a descending trail freezing the seawater altogether. This process results in forming a delicate ice sheets that develops into what has been called a brinicle.
Found mostly in the Arctic and Antarctic, they look like solid thick chunks that resemble a seawater-soaked sponge. Specialists have recorded salt water getting excluded from sea ice and then sinking. When this brinicle touches the sea bed, it freezes every arctic and Antarctic animal that comes into its contact, including starfish and urchins.
This phenomenon was first captured in the time-lapse film of Hugh Miller and Doug Anderson for the BBC One series Frozen Planet. It seems as a race against time as nobody knows how quick they are!