Water

Water, known scientifically as dihydrogen monoxide, was a compound created from the elements of hydrogen and oxygen, and found on many planets in the universe. The surface of planets such as Mon Calamari, Kamino, and Manaan were completely covered in water, and on other terrestrial planets, water was found in oceans, lakes, rivers, and aquifers. Water was a vital commodity for many life forms, while for other species it was poisonous. Bodies of many species consisted of large amounts of water; for example, water was about 60 percent of Human body weight.

Water in its frozen form was known as ice, and in gaseous form was called water vapor, which formed crystals. Sometimes it would condense and fall as snow, sleet, or hail. Planets that experienced consistent ice included Csilla, Hoth, Mygeeto, Ilum, Rhen Var, Anteevy, Ota, Orto Plutonia, Ojom, Rekkiad, and Polus.

In the universe, no liquid was as versatile as water, and very few organisms could exist without it. The unique molecular structure of water gave it several unusual properties necessary to the chemical reactions that sustained life. These properties included its ability to dissolve chemicals, its ability to easily absorb and redistribute heat, its high surface tension, and the fact that it expanded when frozen. Life had a much higher likelihood of developing where water and carbon were present.