I was only in grade school when the pet rock thing hit. It was gone before I even knew what was going on. As I remember, it was only the teachers that got into it, and they made their own...painted faces and glued googly eyes onto them, and felt to the underside, then used them as paperweights.
Part of the reason why I never got into it was that at that time I already had a rock collection. I had fossils, minerals, all kinds of stuff. It seems like my most prized possession was a dinosoar gizard stone. It was given to me by a college professor that was a friend of my dad’s. I have no idea how someone determines if a rock was actually in a dinosaur’s gizard at one time. The last thing I wanted to do was paint a stupid face on the rocks I had in my collection.
So, how did the inventor make his millions when everyone was making their own pet rocks?
It was not the rock, it was the clever packaging and instruction booklet that made millions.
Dunno, perhaps it was the included Pet Rock Training Manual. But the price was $35 per fool.