The question as to whether or not we have received visitors from space can probably only be answered with certainty if and when we find indisputable evidence for such a visit here on Earth. Such a proof could consist of the discovery of artifacts whose exact age can be determined, and whose external and internal structure can be regarded as "time-anomalous". In recent years numerous micro-objects have been found in the Urals, which appear to fulfill these requirements. This is the first published report of the discovery.
UFO Folklore Center