Comment by LadyCailin

I found a seashell in the middle of the forest in (well inland) Mississippi. That was an interesting find, and lead me to learn that much of the continental US used to be covered in a sea, I believe https://en.wikipedia.org/wiki/Western_Interior_Seaway

This means the shell was dozens of millions of years old, and may be the oldest thing I’ve ever held, except maybe some rocks.