This image might make you think of grains of sand, a boulder-strewn landscape, or a mountain range viewed from above. These shapes are actually found at the opposite end of the scale: they are microscopic calcite crystals in a hot-spring travertine deposit that grew from ancient melting glacier waters flowing through what is now Yellowstone National Park. By studying microbial influences on mineral depositions such as this one, researchers can gain information to improve energy production, human medicine, and even space exploration.