A white cylinder, silent, not moving, then poof...gone.

While out for a walk on a clear, cloudless day, I noticed a pure white cylinder shaped object in the sky. It had no wings, tail, or any visible means of flying, was silent,was not moving, or was barely moving/flying at all so as to appear to be sitting still. I watched it in that exact same spot for several minutes when suddenly, it either blinked out or left at such a high rate of speed that my eyes could not track it. It reminded me of the white tic-tac object seen by pilots, shown on TV some time ago, but was not moving.