Blimp or hot air balloon like object just below cloud line, never moved for 30 minutes. Dark to metalic depending on angle.

South Deming, NM, approximately over Columbus, NM, my girlfriend and I spotted a stationary object in the sky while traveling west on I-10 at approximately 2:30 pm local time. We proceeded to keep an eye on the object as we traveled until I-10 curved and it was hard to look back and see it. Duration was roughly 30 minutes. The object did not move, stayed just below the cloud line, and did not change in shape, although the color changed from black (when we were east of it) to silver (when we were directly north), and white (when we were west). There were no visible lights. Clouds moved around it so it was not a cloud. Shape stayed fairly consistent as that of cross between a blimp and hot air ballon, but it was clearly neither.