Next time you’re drinking a frosty iced beverage, think about the structure of the frozen chunks chilling it down. Here on Earth, we generally see it in many forms: cubes form, sleet, snow, icicles, slabs covering lakes and rivers, and glaciers. Water ice takes all these fascinating forms, thanks to its hexagonal crystal lattice. That makes it less dense than nonfrozen water, which allows it to float in a drink, in a lake, and on the ocean.