What can it be? From FL370

Time: 21:01z

Location: Spain FL370

I am a commercial pilot and in today’s flight, cruising at flight level 370 I saw a strange object which seemed to be flying way above us. It’s speed was way faster than ours and it was following a steady path. At some point it disappeared. It had a “long shape” like a missile and a cone of light in front of him. We asked ATC if they knew what was it, reporting it’s apporaximate position but they could not identify it.

In all my years working as a pilot I have never seen anything like that. I took some pictures but very hard to take a good one.

Anyone has any idea of what can it be?