Synthetic shells. Coloured scanning electron micrograph of synthetic, spherical shells which could be used to make medical implants or light- weight materials. The hollow, porous shells are made of calcium carbonate (aragonite). The shells were made by Stephen Mann and Dominic Walsh at Bath University, Britain. They dissolved calcium carbonate solution in oil to make an emulsion. Microscopic, gold-coated polystyrene spheres were then covered with this emulsion. The aragonite was deposited on the spheres. The polystyrene was then dissolved, leaving intact spheres of aragonite. Magnification: x18,700 at 6x7cm size. x15,000 '4.5x6cm'.