It also refers to the transparent, rainbow-shimmering filaments produced by the Pinna nobilis, the pen shell mollusc, to anchor itself to a rock or seabed. The luxurious cloth with a golden gloss woven from the spun byssus is also known as sea silk. Because of the rather exotic, ‘coming up from the depths’ image, it’s sometimes known as mermaid’s gossamer.
“Nor was it enough to comb and to sow the materials for a tunic. It was necessary also to fish for one’s dress; for fleeces are obtained from the sea where shells of extraordinary size are furnished with tufts of mossy hair.”
(Tertullian 160 – 220 CE)