Researchers at the Pohang University of Science and Technology in South Korea have recreated golden sea silk — a legendary fabric lost for roughly 2,000 years — using fibers from the pen shell, a clam cultivated in Korean coastal waters [1]. The findings, published in Advanced Materials, explain not only how to make the material but why its golden color endures for centuries.

Sea silk, often called the "golden fiber of the sea," was prized during the Roman era for its shimmering appearance, light weight, and exceptional durability. It was reserved for emperors, popes, and other powerful figures. The material was made from byssus threads produced by Pinna nobilis, a large Mediterranean clam [1]. Marine pollution has since pushed that species toward extinction, and the European Union has banned its harvesting.

The POSTECH team, led by Professor Dong Soo Hwang, discovered that the pen shell's byssus threads closely resemble those of the Mediterranean clam both physically and chemically [1]. They developed a method for processing pen shell byssus into a material that recreates the appearance of ancient sea silk.

The critical breakthrough was explaining the color. Rather than coming from dyes, sea silk's golden hue is produced through structural coloration — microscopic layered spherical protein structures called "photonin" interact with light to create the shimmer [1]. Because the effect is structural rather than pigmented, the color remains stable over centuries.

Professor Hwang noted the technology opens possibilities for sustainable fashion and advanced materials [1]. The byssus fibers of pen shells have traditionally been discarded as waste.

-- KENJI NAKAMURA, Tokyo