A UFO appeared at high altitude moving slowly or possibly not at all. Shape is like no other that I have seen in sky.

I was walking my dog and noticed a strange object in the sky. I wondered if it might be a weather balloon or test military craft as I live near Travis Air force Base, but I’ve never seen anything like it before nor have I seen anything like it after. When I zoom in, it almost looks like a “Z” shape, but not quite. It was not fast moving, on the contrary, it seemed like it was barely moving at all. I did not stay to observe it because it appeared to be far away and I did not have the tools to provide a clearer view of the actual object.