1.
cocoon
The protective silk casing spun by silkworm larvae before they transform into moths. Also used for cocoons of other insects. Historically important in Japan as the basis of the silk industry.
Cultural note
Silk production (養蚕) was a major industry in Japan from the Meiji era through the early 20th century. Many rural areas in central Japan, especially Gunma Prefecture, were known for raising silkworms and producing cocoons. The Tomioka Silk Mill (富岡製糸場) is a UNESCO World Heritage Site.