The something that I think is cool is called a brinicle. So what is a brinicle (pronounced: brine-icle)? A brinicle it is a vertical column of ice that forms below sea ice. Sea ice is much fresher than the sea water that it forms from. This means that when sea ice forms it leaves a super-saline brine behind. The super-saline brine that is left out sinks through channels within the ice and back into the ocean below. However, this brine has been cooled by its journey through the ice to very low temperatures which are enough to freeze the water around it as it sinks. This forms a column of ice around the sinking plume of brine leading from the brine channels to the sea floor.
Check out this awesome video by the BBC which is part of the new David Attenborough special "Frozen Planet". I won't go on since you can watch the video and hear it from David Attenborough. Here is a link to the article where I originally saw the video and the video itself.
BBC Article: http://www.bbc.co.uk/nature/15835017?ref=nf