Where do you go when you're a fish and you need a skincare treatment? Coral reefs contain natural "beauty salons," lively social hubs of activity where fish "clients" swim up and wait to be serviced by smaller fish cleaners. The little cleaners dart under and around their much bigger clients—even entering their mouths—cleaning their scales of bacteria and parasites like a team of car washers servicing a Buick. Sometimes cleaners even rub against their clients, providing a soothing massage.