Joe Hitchen, Oxford University Physics Department, describe the different stages of sea ice growth and the formation of hollow tubes of ice in the ocean known as brinicles. Every year, millions of square kilometres of the Arctic ocean freeze over as sea ice forms but this growth is controlled by processes on the scale of millimetres and centimetres. At this scale, sea ice is not a pure solid but a mixture of ice crystals and concentrated brine known as a "mushy layer". I will describe the different stages of sea ice growth and the formation of hollow tubes of ice in the ocean known as brinicles. Creative Commons Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales; http://creativecommons.org/licenses/by-nc-sa/2.0/uk/