a brinicle is a column of ice that forms in seawater. the name is a combination of the words "brine", which means saltwater, and "icicle". a brinicle starts forming from the top of the water down. a brinicle freezes everything in its way as it forms. it can reach the bottom of the ocean, where it can also form ice on the seabed. it is dangerous to sea stars and sea urchins living on the bottom of the ocean. they move too slowly to get out of the way. they are very rare and only occur in places where it is very cold, such as antarctica.