gutter treasure

Whilst I am still beguiled by rusty bottle tops and collect them regularly I have found a new treasure and this one is curious making on several levels.
Firstly, I have no idea what they are and what purpose they serve.

Secondly, now I have begun to notice them I see them more frequently. I'm not sure if that's because there are increasingly  more of them or that now they have come into my notice I see them whereas before they slipped in a Foucaultian manner passed my awareness.

So I collected them and kept them on the table in my study by the other treasures of the gutter. Also I began to show them to people and ask if they knew what they were.

So far nobody knows but Tracey sent me this image in an email and Richard tells me they are used in packaging.
So I continue to collect them and ask for new information and  also begin to weave meanings; possible meanings of their origins and functions and await enlightenment!