Several spheres looking like Mylar balloons, but doing incredible manuevers, about 100 yards above.

My son and I were standing in driveway,on a clear day, facing the garage and talking with my brother and his wife, who were standing in the garage. I noticed something shiny floating in the sky, about 100 yards above the garage, moving northwest to southeast. It looked like someone had lost a bundle of Mylar balloons. I called my brother and his wife out of the garage to look. To our surprise, what we thought were balloons, stopped moving across the sky, and started descending in a counter clockwise spiral pattern separated evenly from each other. They dropped in the spiral pattern approximately 30 yards and then paused in a group and just hovered for about 1-2 minutes. The silver looking spheres than started moving southwest, directly over the top of the four of us, while they proceeded to make a v pattern. The silvery spheres than started to change their shape from round to more arrow dynamic at the front, while their color changed to dark black.