Fleur de sel has been collected since ancient times, it is a French salt that forms as a thin, delicate crust on the surface of seawater as it evaporates. One method the salt is gathered is to draw seawater into marsh basins or salt pans and allow the water to evaporate, leaving behind the salt that was dissolved in it. As the water evaporates, most of the salt precipitates out on the bottom of the marsh.
 
Guérande, France, is one of the largest areas that harvest this delicate finishing salt and chefs often seek after Fleur de Sal that specifically come from this region.