I knew right away, because a friend of mine found one at
Caesarea Maritima many years ago and only recently found out what it was. The piece was completely covered in iron oxide and looked like a featureless ball. They soaked it for months in an alkaline chelating solution (EDTA) to reveal the artifact. Here is a page from the
catalog that published the find. I am sorry I don't know the exact source of this page, but the story of the find is very interesting. (click for larger view)
