I have seen a few things in the sky that left me wondering...but I am not expert so I'm not going to say one way or the other.
After having talked to a few old salts with tons of ocean miles, there are some strange things out there, things that you just can't explain. Its a big world.
The strangest thing I have ever seen, was most certainly man made. It happened last year. For about 45 minutes a C130 was doing some crazy crap. Flying so low at points I was sure it was going to crash, buzzed my house so low I thought we were in trouble!
Did some crazy turns, you could hear the engines throttle up and down, crazy crap. The next day everyone was talking about WTF that crazy was doing. The strange thing was all my Sikorsky and Coast Guard group LIS connections, guys that should/do know all about it, were silent. Someone told them to shut up, because all of a sudden no one knows anything. That plane was in Sikorskys air space, BS they knew all about it. Group LIS as well.