Methanethiol (its IUPAC official name) is a colorless gas under standard temperature and pressure, becoming liquid at 6 °C. It is the simplest thiol (thiols are analogs to alcohols, with an SH group replacing OH). Methanethiol has a strong rotten cabbage smell, so that some is added to natural gas to ease leak detection. It is produced by decaying organic matter in marshes and by decomposition of an algal metabolite (DMSP, dimethyl sulfonio proprionate). It is the main sulfur source of some marine bacteria and a possible substrate for methanogenesis. In prebiotic chemistry, its presence allows for the synthesis of the S-bearing amino acid methionine in Urey-Miller experiments (Miller 1974). Methanethiol has been found in interstellar space.