Stationery changing-form object in night sky with an appearance not of this world.

Constantly and rapidly changing black form like a hand opening up and closing or a windsock blowing observed against a complete cloud cover- stationery at the center of the sky (directly overhead). 
Observed during an evening walk; object was so strange appearing and other-worldly that I did not believe my eyes. Upon returning home asked wife to step outside and look overhead.  She was astonished to see this form also.
Date is approximate.  PD