Geoff Gadd, a professor of biology at the University of Dundee in Scotland, learned that when he puts bread mold (Neurospora crassa) in a container with urea and manganese, a mineral called manganese carbonate will form around the spindly arms of the fungus. The trick works because mold secretes the enzyme urease, which breaks down urea into carbonate and ammonium. Carbonate is negatively charged and can bond with positively charged metals like manganese, while the ammonium is what the fungi are eating. When this mass of mold and manganese carbonate is heated up, it's transformed again into manganese oxide, which is a common ingredient in rechargeable batteries. http://www.vox.com/2016/3/27/11306868/bread-mold-battery Research paper: http://www.cell.com/current-biology/abstract/S0960-9822(16)30015-X
