When I see bits, I still tend to pick them up. I have quite a large collection, so I'm not sure quite why I continue to bring them home.
Many years ago I took a piece to a specialist museum back in the UK to ask its age. They kept the piece for a while for analysis, then came back with the answer that it was from the Tertiary period, and was about 13 Million years old.
It kinda puts things into perspective. No doubt after we've made the planet uninhabitable for humans, other plant or animal life will continue for another 13 Million years; leaving their own particular traces.