Water, molecule of life.
Buy the t-shirt here:
Water is a chemical compound with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at standard ambient temperature and pressure, but it often co-exists on Earth with its solid state, ice, and gaseous state (water vapor or steam). Water also exists in a liquid crystal state near hydrophilic surfaces.
Water covers 71% of the Earth’s surface, and is vital for all known forms of life. (from Wikipedia)
Get one of the most important and beautiful molecules in the known universe on a t-shirt.