I identified the plastic envelope for the Cornwall geocoin when I found the "The Brick Warehouse" cache in Kobe, Japan recently. The container was incredibly corroded and fell apart as I extracted it from its location not far (2-3 metres) from the water's edge on the waterfront. I suspect that the geocoin may have also perished from the exposure to salt water. There was a paper thin blackish object of the right size but unrecognizable as a coin.