Much like schools of fish or groups of giggling school girls, bands of Myxococcus xanthus, a social bacterium, travel together. In order to hunt prey efficiently and protect one another these cells must coordinate the way in which they move - or "glide" - together. In this image the gliding of hundreds of thousands of these cells was tracked over four hours. Their paths transition from blue to red according to the amount of time elapsed, with blue as the start time and red as the end time.