Interesting. I heard a Nobel scientist once call this stuff OOPART (out of place and relative time).
Actually, there was a book with the title "OOPArts".
I had it, loaned it out and that was the last I saw of it.
The book is now an OOPArt.
I am not kidding. Really is such a book.
Oopart is the name I heard, too, as in out-of-place artifact. Personally I take the same view on them as Rene Noorbergen did; he suggested they're from an extinct human civilization, most likely the one destroyed in Noah's Flood.