“I’m quite confident that the sample that I handled was PVA butylene rubber,” he said in a phone interview, describing a mix of synthetic rubber and polyvinyl acetate, known as PVA. That polymer, he said, is “the active ingredient in white glue — the kind of white glue you have at home is a very dilute, kid-friendly version of this stuff.”

The mixture, he said, “suggests some sort of industrial adhesive or some sort of material that could be used in a variety of industrial sectors.”