From waste to wonder: Revival of ancient Roman ‘golden fiber’ with pen shells

The golden silk, a luxury once reserved for Roman emperors, has been recreated by modern scientists.

In a study published in Advanced Materials, a research team at POSTECH (Pohang University of Science and Technology) announced they have successfully produced the 2,000-year-old textile known as Sea Silk. They accomplished this using threads from the common pen shell, farmed along the Korean coast. The team’s work also explains the origin of the material’s characteristic golden hue and its famed resistance to fading over millennia.

Sea Silk is a historic luxury textile from ancient Rome, once reserved for garments worn by figures such as emperors and popes. Crafted from the byssal threads (silky filaments used for anchoring) of the large Mediterranean mollusk Pinna nobilis, the textile was prized for being both lightweight and durable. Its most notable feature was an unfading golden luster. Today, marine pollution and overfishing have pushed Pinna nobilis to the brink of extinction, and its harvesting is now prohibited.

“In all of Europe, only one artisan is still permitted to harvest and process Pinna nobilis for Sea Silk,” explained Professor Hwang Dong Soo, a leader of the research team. “By collaborating with this artisan and Germany’s Max Planck Institute, we obtained a valuable sample for our comparative research.”

To find a substitute for the endangered Pinna nobilis, the POSTECH team investigated the pen shell (Atrina pectinata), which is commonly farmed on the Korean coast. Traditionally, the byssal threads of these pen shells were discarded as a valueless byproduct of the food industry.

While their large European relatives produce long, robust filaments, Korean pen shells are smaller and their threads are shorter, a reason they have been largely overlooked by researchers. However, the POSTECH team found that this byproduct was a suitable alternative. “We focused on their core similarities,” professor Hwang explained. “Both mollusks belong to the same family, and their X-ray crystal structures and protein sequences are nearly identical.”

But the path to revival presented its own challenges. The most significant hurdle was logistical: securing the raw material itself.

“We had to ask fishermen to separately collect the byssal threads, which they would normally just throw away,” Professor Hwang recalled. “It took a special request to the head of a fishing cooperative at a pen shell farm just to gather the amount we needed for our research.”

The breakthrough came after years of dedication. Lead author Professor Choi Jimin finally solved a puzzle that had long intrigued Professor Hwang, providing an experimental explanation for the silk’s properties. They discovered its brilliant hue is not a product of dye but of ‘structural color’. a phenomenon where a material’s microscopic structure itself creates color, similar to the iridescent shimmer of a butterfly’s wing

In Sea Silk, this microscopic architecture is composed of spherical proteins that the team named ‘Photonin’. These proteins form precise multi-layered patterns, and the orderliness of this alignment determines the vividness of the golden hue: the more brilliant the pattern, the more brilliant the color. Because this color is an intrinsic part of the physical structure, the fiber is exceptionally lightfast and experiencing almost no discoloration over centuries.

The study’s significance lies in demonstrating how a discarded industrial byproduct can be converted into a high-value material. As a practical first step, the research team is now collaborating with a clothing and textiles department to weave the Sea Silk into actual fabric.

Professor Hwang suggested that potential applications could extend far beyond textiles, envisioning uses in luxury apparel, cosmetics, and even as a high-end culinary ingredient.

“If you grind the Sea Silk, it resembles gold powder,” he explained, “and since it’s a protein, it’s edible.”

The story was produced in partnership with our colleagues at Popular Science Korea.

 

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