It’s an animal fiber, used by man for more than 3000 years.
It consists of the thread, or slime, produced by a caterpillar, the silkworm (Bombyx mori), which feeds exclusively on mulberry leaves.

The drool is emitted in double filament which, in contact with the air, solidifies; it’s necessary to the worm to create the cocoon in which to close itself at the end of its life in the form of a larva.

Silk is a tenacious fiber that is very resistant to the aggression of external agents; it is also elastic, flexible, light (the filament is in fact very thin) and has a great luster and brilliance.