The first cultured pearls were produced by the Chinese in the 14th century. These were in fact half pearls made with small Buddha shapes formed out of lead and introduced, as the nucleus, into the shell lining of a freshwater mussel. The mussel was returned to the water in a lake or pond and left for many months. The mother of pearl material that covered these Buddha shapes was nacre, the same type of nacre that forms a round pearl, except for that the layers were half round instead of fully circular.