Ever heard of a brinicle? Nor had we - until we stumbled upon this video, which shows a bizarre 'icicle of death' forming underwater in Antarctica. Scroll down for video.
Using time-lapse cameras, BBC filmakers Doug Anderson and Hugh Miller captured images of this amazing phemomenon for the first time in history.
Brinicles are webs of ice that freeze everything they touch - including living things such as sea urchins and starfish.
This video was taken from BBC1's series, Frozen Planet