Large black UFO Sighting through windshield by two airline pilots

I am an airline pilot for a major airline. At 10:45 local California time on Nov 19th 2018, we were at 35,000 feet over Avenal, Ca. As I was heads down briefing the descent profile into LAX, I saw a large black UFO go through my windshield view. I was initially startled, and my first officer looked to catch a glimpse. I asked ATC if there was any traffic in the area and he responded that closest traffic was 20 miles away. The other traffic was behind us at the same altitude heading same direction. They did not see anything. I’m not 100% sure what I saw because I caught it in my peripheral vision and saw it go by very fast. It was a large black UFO Sighting that had no wings and did not leave a contrail. I am also not sure how close it was, but I do know that it was closer then the normal thousand foot separation of other aircraft. nuforc.org