The bits and pieces of shattered machinery were uncovered by the Mayor of Nowa Wieś Wielka in Dolny Śląsk, north-central Poland, after crash landing in his field.
The bizarre fragments resembling a broken rocket were covered in undecipherable writing of unknown origin.
Police officers who were immediately alerted to the incident concluded the mystery object fell out of the sky.
Kordian Mazuryk, Jawor Police spokesman, said: “On May 22, just after 10am, we received a phone call from one of the local residents, specifically the Mayor of one of the areas near Jawor, about a bizarre finding in his field.
“After our police officers were dispatched, it turned out the fragments resembled an aeroplane fuel tank.
“The object was shattered into fragments and we secured them to establish their owner and origin.”
But the did the mystery fragments belong to a damaged UFO or another extraterrestrial visitor to Earth?
Highly unlikely, according to the Polish Civil Aviation Authority and the Committee for Investigation of National Aviation Accidents.
Instead, the two agencies concluded the mystery aircraft fragments belonged to a Czech MiG-15 fighter pilot.
Mr Mazuryk said: “The object comes from a military aeroplane, which took part in an airshow in Ławica and was returning to the Czech Republic.
“It was a Czech armed forces’ MiG-15 which suffered a failure of its electrical systems and lost two of its suspended fuel tanks.”
Both of the fuel tanks were empty when crash landing which spared Nowa Wieś Wielka from a spectacular explosion.
However Mr Mazuryk stressed the incident could have been extremely dangerous because the pilot could not tell when the tanks were dropped.
The MiG-15 pilot reported the incident immediately after landing back in the Czech Republic and the appropriate authorities were alerted.
Officials are now combing local areas to uncover the second of the ejected fuel tanks.
Mr Mazuryk said the second tank will most likely be found within the Jawor area.