Crystals can be found on the surface of the cocoons loosely attached to the silk fibres. Fig. 7 shows the crystals with different morphologies in different scales. Most crystals on the cocoons in this study have a cubic shape with a side length of 1–3 μm (Fig. 7A–D for cubic crystals on different cocoons in different scales). Only G. postica cocoon has been found to have columnar crystals of 20–30 μm ( Fig. 7E and F). The crystals are usually on the outermost surface of the cocoons. But for A. roylei cocoon, which has a double cocoon structure, the crystals are found on the outer surface of the inner cocoon ( Fig. 3). The crystals are not found on the attached surface.