Cerebos is an English brand of salt and, more recently, other flavourings and nutritional supplements. Its promise was "See How It Runs", because it contained anti-caking agents; at the time of its introduction, salt was sold in large blocks from which the user would scrape what they needed. Free-running salt was a novelty because, left for any length of time, pure sodium chloride crystals would absorb sufficient moisture from the air to cause them to stick together, a phenomenon called caking. A boy chasing a bird and pouring salt over it is an icon that has become synonymous with the brand.