For anyone in need of the perfect pet - low maintenance, cheap, and obedient - Gary Dahl offered the perfect solution: Pet Rocks. In April 1975, Dahl, a Californian working in advertising, was joking with friends about how he had the ideal pet. His pet never misbehaved, made no mess, and didn't cost a lot of money. His friends helped him extol the virtues of a "pet" rock, and a fad was born.

During the next two weeks, Dahl wrote The Pet Rock Training Manual, an manual for owners who wanted to have a good relationship with their pet rocks. The manual contained instructions for teaching your pet rock tricks such as how to play dead and roll over, as well as how to house train your rock. Owners were instructed to place their pet rocks "on some old newspapers. The rock will never know what the paper is for and will require no further instruction."

After the manual was written, Dahl created a pet rock to go with it. He bought a Rosarita Beach Stone at a builders' supply store. This stone, a round gray pebble, was the most expensive stone in the store. Dahl packed it in excelsior in a pet carrying case gift box, added the manual, and the first of more than 5 million Pet Rocks sold before the fad went out of style.

The Pet Rock was first sold in the San Francisco area, then caught on and spread to New York. Neiman-Marcus ordered hundreds of Pet Rocks to stock their stores, and their creator appeared on The Tonight Show with Johnny Carson. Dahl sold his Rocks for $3.95 US Dollars (USD) each, almost instantly becoming a millionaire. The fad was quickly over, leaving Dahl with leftover Pet Rocks that were relabeled as Valentine's Day gifts, but didn't sell.

Originally, the Pet Rocks were simply plain rocks, but personalities were quickly created, including rocks with faces painted on them, birth certificates and "papers," and several pebbles sold together as a family of Pet Rocks. Copycat versions of Pet Rocks were also sold, including one brilliantly named one: "The Original Pet Rock."

Pet Rocks may have been a short-lived fad, but they marked a memorable moment in the 1970s and in the history of silly fads. Many people who remember the 1970s think fondly of their own Pet Rock, proving that marketing really is everything, and that Americans will buy anything, no matter how truly useless it is.