Natural pearls are formed when an foreign object becomes trapped in the shell of an oyster or pearl and the animal surrounds the object with several mineral layers in order to protect its soft tissue. Most pearls sold today are farmed pearls, created by intentionally inserting small mother-of-pearl beads in the oyster's shell. The resulting pearls are harvested up to two years later. Pearls come in a range of pastel colors from cream to blue to pink, and irregularly shaped pearls are often called "baroque" pearls. Mabe pearls are hemispherical cultured pearls grown against the inside shell of an oyster rather than in the mollusk's body. Mabe pearls are typically used in settings such as that conceal their flat backs.