I never had an interest in UFOs until I saw one here in Montana. The year was 1976. The following year, 1977, I purchased a helium neon laser, and signaled the various objects operating in the sky. The objects reacted instantly to the laser beam. They would slow down, hover, change direction and fly directly over my position. There was an explosion of activity that summer. I never have seen so many craft operating in the sky, at low altitude, before or since. A huge hemispherical shaped craft flew directly over my position at low altitude. The outer surface was completely smooth. No engineering features, whatsoever. As if the craft was cast as a solid. It had a white metallic surface. There was a faint white glow, emanating outward from the surface, equally over the entire surface area of the craft. It travelled in an absolutely straight, and stabilized, horizontal orientation, and trajectory. It made a powerful low frequency roaring sound, as it flew overhead. That is the one, and only time, I heard sound coming from a craft. All the others were silent. This craft was different than any other craft I���ve seen. Words can���t adequately describe what I felt and experienced, during that fantastic instant, in space and time. Advanced technology!!!! Whewwwww. This is what the craft looked like.Sincerely, Darryl Broome