Zig zagged across face of moon

Driving my kids to school. Some clouds, but none near the moon. Noticed an almost black area towards the notion left. Moved to the right side over the crater, and then to the middle, Middle left of the top
The closer it got to the top, the smaller in height, not width, it became, until it was gone, as if it went around. There was nothing above the moon, no clouds, no aircraft, after it disappeared
No lights, just a black mass