During the archaeological excavations, mining works, sometimes just by chance in the strata of the earth are the items that baffled not only the miners, but also scientists and researchers.
They are called fossil unidentified objects (NCI), or artifacts. Typically, NIO consist of one or another metal. A puzzle blocked – that they occur in the rock layers historically coincides with the time when the world in principle could not only be treated, but simply any one smelted metal.