Freshwater pearls are a kind of pearl that comes from freshwater mussels. They are produced in Japan and the United States on a limited scale, but are now almost exclusive to China. The U.S. Federal Trade Commission requires that freshwater pearls be referred to as "freshwater cultured pearls" in commerce. Baroque pearls are simply pearls that have an irregular shape. Cultured freshwater pearls are most commonly baroque, because freshwater pearls are mantle-tissue nucleated instead of bead nucleated. Thus these pearls are rarely perfectly spherical and can appear oval.