Dark S-shaped UFO descended from below the clouds, all the way to the ground, out of sight behind houses.

Okay I swear on my life this happened. It was a few years ago. I guess 2012-2016 because that's the era of my ending-childhood that mixes for me, and I know for a fact it was in one of those years.  There were 6 other witnesses with me, all of which my siblings, all of which a few years younger/older than me. I was outside of my home, standing on my driveway (in the suburbs) when I look up and see it.
It's cloudy outside, and there's a distinct thing spinning under the clouds. It was the shape of an S. It reminded my little-kid mind of a worm, but it was the shape of an S. It was dark, dark gray, and more like black. There were no lights or anything. It was falling, but more like descending because it wasn't free-falling or anything. It was a flat S, sitting horizontally in the sky. It was spinning at the rate of like three seconds for one rotation, also horizontally. Me and my siblings all stood on the driveway shouting and staring at it. Our mom heard us from inside and told us to be quiet. For some reason she didn't come out and look?? Even though we obviously were seeing something.
We had a theory that it was something for the military, or a foreign military, but that the last-case scenario was that it was a UFO. I've never believed in aliens but I need to know what this was.