You may have heard the story of the Pet Rock, the Mexican beach stone that could be purchased in bulk for less than a penny, retailed for $3.95, and made inventor Gary Dahl a millionaire during a kind of novelty gift hysteria in late 1975. But Dahl didn’t really get rich off of the rock.

He got rich off of a cardboard box.

Dahl was working as a freelance advertising copywriter in California that year when, while having drinks at a bar with friends, the conversation turned to the destructive nature of pets. Dogs and cats ruined furniture. Worse, they required constant attention, from being walked to being fed to cleaning up after them. Dahl said that he didn’t have to worry about any of that because he had a “pet rock.”

It was, of course, a joke. And it got a laugh. But Dahl decided there could be more to it than that. He went home and began writing an owner’s manual for this hypothetical pet rock, which detailed how best to handle it, the tricks it could perform (“play dead” being the most popular), and how it could remain a faithful companion due to its “long life span.” The gag was not so much the rock itself but the way it was presented. In addition to the manual, Dahl conceived of a cardboard box with air holes that resembled the kind used by pet shops. It also bore a passing resemblance to a McDonald's Happy Meal container.

 

Dahl's motivation in making a serious effort to monetize his pet rock idea was due in large part to his precarious financial situation at the time—he was struggling to keep up with his bills. He recruited George Coakley and John Heagerty, two colleagues, to come on as investors. They both signed on, with Coakley investing $10,000—a not-inconsiderable sum in 1975, especially when the intention was to sell virtually worthless rocks.

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Dahl, however, knew what he was marketing. Like chattering teeth, the Hula Hoop, and other fads, the Pet Rock was the beneficiary of good timing. Vietnam had ended but Watergate was still fresh; the country’s mood was slightly downcast, and Dahl believed people would see the inane nature of the Pet Rock and recognize the humor of it. He boxed the rocks with the manual and packed them in excelsior, which may be best known as comic book legend Stan Lee’s catchphrase but also means a softwood shaving pile meant for protecting fragile items. The rocks were purchased from a local sand and gravel company, which sourced them from Mexico’s Rosarita Beach. Dahl debuted the rock at a gift show in San Francisco in August of 1975, then waited for a reaction.

He got one. People understood the appeal right away and he began taking orders. Neiman Marcus wanted 1000 rocks. Bloomingdale’s later signed on. Newsweek did a story with a picture, which spread the word. Dahl had retail and media credibility for what was superficially a nonsense product. His bar joke was turning into a national phenomenon.

When the holiday season arrived, Dahl estimated he was selling up to 100,000 Pet Rocks a day. Ultimately, he would sell between 1.3 and 1.5 million of them within a period of just a few months. Coakley made $200,000 back on his initial $10,000 investment. Dahl gifted both Coakley and Heagerty with Mercedes. Making 95 cents in profit on each Pet Rock sold, Dahl earned over $1 million. He launched his own firm, Rock Bottom Productions, which was itself another joke. “You’ve reached Rock Bottom” is how the receptionist answered their phone.

 

The fad did not last—by definition, they’re not designed to—but Dahl was satisfied. His two investors were not; they "claimed they had received too small a share of the profits" and later sued Dahl for more revenue. After a judgment in the investors' favor, Dahl wrote them a six-figure check.

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There were attempts to prolong the life of the rock by offering a Bicentennial version in 1976—it had the American flag painted on it—and mail-order college degrees for them. Dahl sold Pet Rock T-shirts and Pet Rock shampoo. There were also copycat gifts, since Dahl could not really patent a rock. (He might have been able to obtain a utility patent because of the rock’s particular purpose as a companion, but he did not.) The humor was transient, however, and people had moved on.

Dahl had other ideas. There was the Official Sand Breeding Kit, which claimed to provide guidance on growing sand, and Canned Earthquake, which consisted of a coffee can that had a wind-up mechanism that caused it to jump around on a table. Neither was particularly successful. Dahl’s real passion, though, was buying and renovating a bar in Los Gatos, which he named Carrie Nation’s Saloon.

This was not without its problems, as people who believed they had the next Pet Rock would often stop by the bar to try and secure an audience with Dahl for his insight. Many times, their idea consisted of packaging bull or elephant excrement. There were also proposals to market a pet stick. Dahl had no patience for these inventors, believing the Pet Rock could not be duplicated. Later, he went back to advertising after taking what he described as an “eight-year vacation” following the success of his project.

The Pet Rock can still be found online, though it’s no longer Dahl’s business. He died in 2015. Of the unsold rocks he had left over at the end of the fad, he was indifferent. If they didn’t sell, he said, he would just use them to repave his driveway.