I wonder if they ever come upon a whole one. Wonder what other kinds of things are mixed in with the olive oil amphorae. In the picture it looks like only the amphorae are there.
Near the end of the article (which didn’t show up in the online version, I’d just read the whole thing in a “Classical History” special issue, very nice btw) there’s a find of a nearly complete one, the bottom is however missing. There are marks made in the clay before firing, that’s how the fragments are dated. And most of these were used for olive oil, shipped from Spain, and probably never reused.