To be noticed that the spiral grains on the surface of nacreous layer of Hyriopsis schiegeli shells and its pearls are rarely found in other fresh water cultured pearls.

• 值得注意的是，在池蝶蚌贝壳及其珍珠的珍珠层表面出现螺旋状纹理，这种现象在其它的淡水珍珠（如三角帆蚌贝壳及其珍珠）中极为少见。