It sounds like a germaphobe’s nightmare: an object that’s not just crawling with bacteria but literally made of the stuff. As detailed by Chemeurope.com, at team of researchers from the Living Materials Laboratory at the University of Colorado Boulder created “living concrete” by allowing photosynthetic cyanobacteria to grow on a scaffolding of hydrogel and sand. The process resembles the formation of seashells, with moisture fostering bacterial growth and mineralization. Bacterial concrete not only has the potential to be a sustainable building material; it helps build itself. If you cut a living brick in half, the bacteria will grow into two whole bricks with the addition of hydrogel. Perhaps best of all, since this concrete partly derives from sand, if you used it to build a house, your home would be your sandcastle.