Researchers in Bonn have discovered a Roman Superglue that was used to attach silver plates to an iron helmet. It was discovered when the heat from a microsaw that was being used to separate a silver plate from the helmet caused the glue to melt and the plate fell off, drawing mysterious threads.

They have isolated bitumen, beef tallow, and pitch made from tree bark. Other ingredients may have included brick dust, soot, or quartz sand. They still haven't worked out the proportions.

Story in German here.