Oh, what a sticky web they wove.

A look inside a piece of 130-million-year-old amber found in Lebanon has revealed a gossamer treasure: a filament of spider silk laced with sticky droplets that look just like those from modern spiders.

The 4-millimeter-long strand of viscid silk--the glue-covered type that some web-spinning spiders use to capture prey--is more than 90 million years older than any known sample of spider silk.

Despite its age, the strand has hallmarks of modern spider silk, says Samuel Zschokke, a biologist at the University of Basel in Switzerland. For example, most of the filament's glue droplets range from 7 to 29 micrometers in diameter and are arranged in an alternating sequence of small and large. Zschokke describes the delicate fossil in the Aug. 7 Nature.

Both modern orb-weaver spiders and comb-footed spiders spin this type of silk. If the fossil filament came from an ancestor of one of those varieties, it was probably a comb-footed/spider, says Zschokke. Today, those arachnids are the only ones that spin webs bearing viscid silk near tree trunks, where seepifig resin would be likely to trap a stray strand of silk.--S.P.