Flying Saucer???

I have never seen one of these before, and I was puzzled when I saw it.  It was in the middle of the road so I assumed it was a modern version of a Cats Eye.  But I could only see this one, which just adds to the puzzle. And the central ball does not depress when you stand on it, which the original Cats Eye does.

We had gone to Padley Gorge with our daughter in law and two grandchildren to pick Bilberries. The children picked quite a few, but very few survived to reach home!