Similar to the disappearance of glass fishing floats. We used to get a lot when I was a kid that washed up from Japan. All the way from small ones (either round or elongated) to round floats a foot or two in diameter.
They have been using plastic floats for a long time now, so finding a glass float is quite rare and they are now worth a lot of money.
We’ll see what charming affect nature has on plastic. Should be about three thousand years.