Snow crystals are crystals that have formed around tiny bits of dirt that have been carried up into the atmosphere by the wind. So snow crystals are really soil particles that have been dressed up in ice.
Scientists think that there are really four different shapes of snow crystals.
The simplest shape is a long needle shaped like a spike. The other shapes all have six sides. One of them is a long, hollow column that is shaped like a six-sided prism. There are also thin, flat six-sided plates. And lastly there are intricate, six-pointed stars.