I'm reminded of one of the (very few) times that John W. Campbell published a photo on the inside back cover of Analog (or it may have still been Astounding.) It looked like a bizarre cityscape of stepped towers rising from a plane, and had an accompanying blurb describing the ancient alien city of Ledtintel. In fact, it was a photomicrograph of lead tin telluride crystals.

(The other time JWC printed a photo, it was a lovely shot of a rocket launch, with flame and smoke billowing around the pad... except that the rocket was just sitting there, and the gantry tower was lifting off. Trivial now, but pretty cool a couple of decades before Photoshop.)