I wish you'd known I had a table at that show, and brought it to me. I'd have explained it for you there.
We relic-diggers often find the CS copper timefuze adapter plugs with remnants of the paper-bodied timefuze in them. The paper is preserved because while the fuzeplug was laying in damp ground the paper got "impregnated" by copper oxide, which is toxic to the insects and bacteria etc which would normally eat the paper. That's the same reason brass buttons are sometimes found with cotten thread still intact in the loop. Toxic metal oxide impregnation is also why lead bullets sometimes get dug with remnants of the paper cartridge still well-preserved on them, and some "lead-filled" buckles, breastplates, and boxplates get dug with a chunk of the leather they were mounted on still present on their back.
Regards,
Pete