A Russian expedition to the Tunguska explosion site has made a claim that they have found a "technical device" supposedely from a UFO that they believe crashed there in 1908. Before their expedition, they said: "We intend to uncover evidences that will prove the fact that it was not a meteorite that rammed the Earth, but a UFO" - clearly stating their intention and showing that the search was not an unbiased one. Soon after making that declaration, sure enough, they claim to have found something! What a surprise.
The facts of the case clearly point to a small comet or asteroid entering the atmosphere over Siberia on June 30, 1908 and catastrophically disrupting about 8-10 kilometers above the surface of the Earth, releasing about 15 Megatons equivalent of TNT worth of energy into the atmosphere. The body was pulverized to dust in the explosion and likely blew away in the wind while the energy released knocked trees down and ignited forrest fires under the explosion site. Observations by witnesses saw the fireball during its entry and saw the explosion, which looked a great deal like a nuclear explosion. Recent modeling of the event has confirmed the basic ideas and the biggest debate is over whether the object was a stoney asteroid or a comet. There is no need to invoke magic or UFOs or micro black holes or swamp gas to try and explain the event. We know Earth gets hit by meteors all the time and we can estimate the frequency that an object of the size that generated the Tunguska event hits Earth and that is probably once every few hundred years, plus or minus a factor of a few. If these folks actually found some real evidence, then that will be a first and we will certainly be happy to change our opinion, but if, as in previous cases, their claims are unsupported by real evidence, then science has no reason to change its consensus on this event that it was anything but natural.