Clay pottery is one of the oldest ceramic utensils used by humans in food preparation. Its unique properties and the sourcing of raw materials have been used since ancient times for the preservation and preparation of food. Notable are its properties for use in both cold and heat for much longer periods, and the preservation of the natural nutrients of food. Flavor with tradition from Portuguese Clay Pottery. Produced in Portugal since 1977. When stored, clay pottery should be well dried, as being unused for a long time, mold formation is natural, a perfectly normal process due to the high porosity of the clay that absorbs all moisture.