Peter Trimble found his formula through trial and error. A design student at the University of Edinburgh, he was aiming to produce an artistic exhibition for a module on sustainability, when he stumbled on "Dupe," a living alternative to concrete.
A lab technician introduced Trimble to Sporosarcina pasteurii, a bacterium with binding qualities, sometimes used to solidify soil to hold road signs in place. The student tested it with one of the world's most abundant resources - sand. Pumping bacterial solution into a sand-filled mould, he added nutrients, urea derived from urine as fertilizer and calcium. After a year, and hundreds of failed experiments, this process manufactured a stool around 70% the compression strength of concrete.