Besides the Antikythera mechanism and the Maine Penny, both of which seem to have plausible explanations, are there any other anomalous artifacts that historians and archaeologists accept as highly unusual? Besides the usual suspects like The Baghdad Battery and The Dorchester Pot which are questionable at best?
Edit for clarification: Are there any anomalous artifacts whose authenticity and date are not in question?
The issue here is that if its authenticity and date are no longer in question, it's no longer anomalous. If I'm digging and find a longsword in ancient Peru (which is ridiculous), and everything checks out to be authentic, then the theories and ideas change. I don't stick it in some box of anomalies for stuff to be figured out later. Pretty much any "revolutionary" archaeological first would have been an anomaly at its time, simply for being the first one found.