And yes I know about these things because of a british show called "Conspiracy" that came to netflix.
There is one about aliens with a weird example they can't explain. Guy says he was in the woods and a UFO showed up close to the ground, dropped some spiked object that rolled at him and hit him and he was knocked out. Woke up and it was gone. He saw a bright light before passing out.
This was explained away as him having a seizure or something. A bright light is common. Only issue was...there were actually tracks in the forest matching his description of spiked metal balls rolling at him. How'd they get there if it was just a seizure?