Just imagine, you are sitting on a sunny beach, contentedly letting the warm sand trickle through your fingers. Millions of sand grains. What you probably can’t imagine: at the same time, billions upon billions of bacteria are also trickling through your fingers. Between 10,000 and 100,000 microorganisms live on each single grain of sand, as revealed in a study by researchers from the Max Planck Institute for Marine Microbiology in Bremen. This means that an individual grain of sand can have twice as many residents as, say, the city of Fairbanks, Alaska!