A crystal dagger of unknown origins
In 1980 archeologists began excavating a megalithic tomb in Southwestern Spain. What they found inside was a true treasure trove of prehistoric objects. Among the items, they found this crystal dagger which was believed to have some ritualistic function. But this was not the only puzzle they encountered.
The site was home to many other rock crystal tools, as well as to twenty sets of human remains. The bones contained high amounts of mercury, and it is not known if they all died simultaneously as part of a ritual or if they were merely buried in the same tomb.