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Golden Fiber Worn by Emperors Resurrected After 2,000 Years
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One of the most prized materials of antiquity—the luxurious "golden fiber of the sea" that was reserved for the likes of Roman emperors—has been resurrected after 2,000 years.
Often proposed as the inspiration for the "Golden Fleece" of Greek myth, sea silk is made from the "byssus" threads secreted by the pen shell Pinna nobilis, a large species of clam that is native to the Mediterranean, to anchor it to rocks on the seafloor.
Sea silk was valued for being lightweight, warm and finer than regular silk, but also for its iridescent, golden color that wouldn't fade.
A sample of the new sea silk.
A sample of the new sea silk.
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Ecological decline, overfishing and marine pollution, however, have driven P. nobilis into endangered status, with harvesting of the clam has been banned and the art of spinning byssus thread now limited to but a few individuals.
Now, however, professor Dong Soo Hwang of South Korea's Pohang University of Science and Technology and colleagues have spun sea silk from the "waste" byproduct of a commercially farmed shellfish—and revealed the secret of its lasting color.
In their study, Hwang and colleagues focused on another "pen shell" species, Atrina pectinata, which is cultivated off of the coast of Korea for food.
Just like its endangered cousin P. nobilis, A. pectinata secretes byssus threads to anchor itself to the sea floor.
The researchers determined that these threads are both chemically and physically similar to those produced by P. nobilis—and, moreover, can be processed to recreate golden sea silk.
Analysis of this material has revealed what gives sea silk its distinctive golden hue and why the color is so resistant to fading over time.
Rather than being the result of some form of dye, the golden sheen of sea silk is inherent, a form of "structural coloration" derived from the way light reflects off its nanostructures. The same phenomenon can also be seen at play in the iridescent surfaces or soap bubbles and on butterfly wings.
Pictured: a pen shell, both closed (left) and open (right), showing the byssus from which the material for the sea silk is taken.
Pictured: a pen shell, both closed (left) and open (right), showing the byssus from which the material for the sea silk is taken.
POSTECH
In the case of sea silk, the structural coloration come from the layering of a spherical protein called photonin—one that becomes more vivid the more orderly the protein arrangement. The result is a coloring that is highly stable.
"Structurally colored textiles are inherently resistant to fading," said Hwang in a statement.
"Our technology enables long-lasting color without the use of dyes or metals, opening new possibilities for sustainable fashion and advanced materials."
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Reference
Choi, J., Im, J.-H., Kim, Y.-K., Shin, T. J., Flammang, P., Yi, G.-R., Pine, D. J., & Hwang, D. S. (2025). Structurally Colored Sustainable Sea Silk from Atrina pectinata. Advanced Materials.
