The solid state of water is commonly known as ice. In this form, water molecules are arranged in a structured, crystalline lattice, which makes ice less dense than liquid water. This unique structure allows ice to float on water, a crucial feature for aquatic life. Ice forms when the temperature drops below 0 degrees Celsius (32 degrees Fahrenheit). As water cools, the molecules lose energy and move closer together, eventually locking into a solid structure. Ice can occur naturally in various environments, such as glaciers, snow, and frozen lakes.