silkworm (Bombyx Mori) cocoons. This is a natural source of silk before it's processed.Natural white cocoon or silkworm nets for background, a source of silk thread and silk fabric Shutterstock Image - silkworm (Bombyx Mori) cocoons. This is a natural source of silk before it's processed.Natural white cocoon or silkworm nets for background, a source of silk thread and silk fabric - ID: 544613884