These artifacts have come from three seas - the Atlantic, the Pacific and the Mediterranean - over the years. As well as various and sundry rivers, creeks, lakes and the like.
There are a few sharp edges but the rolling of waters has smoothed the surfaces in most cases. I find pleasure in the smooth and unpredictable bends and the round shapes caused by the constantly flowing water. It is difficult to comprehend how something as soft as water can abrade the rocks into such curvaceous bodies.
And then there are signs of some forms of life which have etched the surfaces.
You can spend a long time on a warm afternoon contemplating this and trying to ascertain what came before.
It's a pleasant way to avoid the news of the world and escape into a reverie where more mundane things don't matter.