This aircraft was making maneuvers that are not physically possible by any known aircraft in all the militaries of the world.It was foggy out, in the bay in the late summer early fall, the fog literally rolls right over the bay. It was late after-noon early evening. The craft was blackish/greyish, with a glossy or shine to it. It was circular disk shaped, it was doing aerobatics, it seemed to be playing around. The craft was very agile, turning very quickly,swiftly and gracefully. It than proceeded to flip around or barrel rolled diagonally very sharply, it flipped around in different positions 3 times, i drew out a diagram and the directions of which it was conducting its aerobatics. it continued flying at a complete vertical up and down angle before disappearing back into the fog.