5 blacked out aircraft in perfect formation flying north to south at approximately 500 feet at a speed of around 150 - 175 kts

Firstly, I don't believe in UFO's, ancient aliens, and all that; however, as an air traffic controller, retired Air Force, and commercial rated pilot I am fairly confident on how to identify an aircraft. At approximately 2000 hours while watching my dog do her thing, I noticed (briefly) 5 chevron shaped objects that were blacked out but gray in color moving at a moderate speed at or below 500 feet traveling North to South in a perfect V-formation. They were without strobes and position lights and lacked any noticeable sound. There were no vehicles driving by that would have illuminated structures casting a shadow into the sky (the sky was partly cloudy at the moment; few clouds that were visible); geese that fly in formation always make noise while in flight but there was no noise and no jagged formation movement...and, I rarely have seen/heard geese flying at night. I know what I saw, and these were definitely objects that could not be classified and definitely were not drones of any kind. Although close to an airport, I do know that these objects were not an aircraft; at least not listed in Jane's book.