I saw a black bar in the clouds then as it came closer it turned on its side to face the plane.

My seat was 4E and my husband 4F next to the window. I saw this black bar and initially thought that I was imagining it so I keep looking and the bar increased in length as it neared the plane. As my husband was eating and is hard of hearing I did not interrupt him and I did not want to be distracted from looking. When it turned on it's side, I could see that it was at least a third of the size of the plane, at a guess. The full view only lasted about 10 seconds then it turned back so it only looked like a black bar and continued to travel away from the plane to the rear. It looked like a black smudge as it was leaving. The captain and his second came out of the cockpit as we were departing but unfortunately I did not ask him if he saw it too but I do believe that the both of the pilots MUST have seen it. I have tried to contact the airline but that was impossible and I tried to contact other agencies without success. I could see no windows/openings, no propulsion devices, no lights just the structure of the vehicle. If you could contact the pilot that would be great.