Any pilots seen a UFO?

-Just curious-Yes. I'm not saying I saw a flying saucer with little green men inside though. I did, however, see something in the sky that I could not identify. Several other airline pilots saw the same thing I did, two of which were coworkers who were on a flight that was at least 80 miles away from us at the time.
A UFO by the literal meaning means a plane that cannot be identified by a radar, by that, I have. A science fiction UFO is different. I don't believe in them personally nor have I seen any.
I saw a hawk fly into a cloud at 6000 ft. last week.



I could tell what it was, so I guess it was not a UFO.



However, it was not something I wanted to challenge for airspace.
Google the name "John Lear" - You will get plenty about UFOs -

John Lear is a retired Tristar captain...
I'm not a pilot, but I have seen one.
My cousin is a pilot and he has.