UV light reveals hidden patterns on seashell fossils

Under natural light, fossilized seashells appear devoid of color (top row). But under ultraviolet light, they appear bluish and patterns emerge (second row). Fluorescence hints at the presence of dark pigments, so reversing the UV images reveals what the shells probably looked like millions of years ago (third row).

Jonathan Hendricks

By Helen Thompson

April 3, 2015 at 2:30 pm

To the naked eye, fossilized seashells lack the colorful patterns of their living counterparts. But ultraviolet light can reveal some of their unique hues using a new method described by San Jose State University geologist Jonathan Hendricks on April 1 in PLOS ONE.

While examining 4.8-million- to 6.6-million-year-old cone snail shells from the Dominican Republic, Hendricks found that under UV light the organic compounds in the shells fluoresce — though it’s unclear which specific compounds are doing the fluorescing. Using images taken under UV light, Hendricks re-created the shells’ pigmentation, compared the patterns and identified snail species. Out of 28 species, 13 are previously unknown, and one fossil shell even sports polka dots.