Compiled from Origins of Chinese Art and Craft
Cocoon is a type of grayish white fluid which is secreted by the silkworm. It is made out of silk protein and silk glue which hardens upon contact with air. Silk is malleable and elastic. A silkworm can secrete about 1,000 metres of silk thread.
Picking Mulberry Leaves
As silkworms feed on mulberry leaves, mulberry trees were grown in abundance. The job of picking mulberry leaves was usually left to the womenfolk. Characters like mulberry, cocoon and silk were already found in the earliest Chinese writing: the shell-and-bone writing.