What was the Shroud from Manoppello made from?

The Manoppello Image is an image of a face, often supposed to be Jesus, on a cloth that is stored in a church in the village of Manoppello, Italy. The cloth has been claimed to be made of a rare fiber called byssus, which is a natural fiber coming from a bivalve mollusc Pinna nobilis, woven into sea silk, and used by ancient people mainly around the Mediterranean coasts. There have been claims that the cloth is the Veil of Veronica.