This must be a magpie's feather. Iridescent and glowing with petrol puddle brilliance.
When I am running, strangely, I seem attuned to, attentive to, the world around and beneath my feet more markedly than ever.
After this feather I found a fossil. My first fossil. It was mud covered and I couldn't tell if it was a shell stuck to a stone with concrete, plausible, but unlikely perhaps in the middle of a field. When I had cleaned it, however, the fossil-iness was revealed.

And then today, a cloudier day, I took the dog out - just walking, not running - and I passed places where the thrushes hammer open snail shells on convenient stones.

This world of entangled life. From thousands of years ago to today. Life and death in an ongoing dance. The traces of such even small existences are not ever entirely lost.
I am impressed with your finds. That stone does look very fossil-like - some ancient sea weed or gingko leaves look a bit like they (and apparently gingko trees have been around for a long, long, long time). I was just reading about your thrushes. Smart birdies. I've seen gulls do that with clams on nearby paved roads. I like very much how you end the post - that last sentence.