In 1975, Gary Dahl created the Pet Rock after joking with friends about low-maintenance pets. The novelty toy required no care and thus surprisingly became a hit during the period. It came with a humorous training manual on how to “care” for your rock. The novelty toy became a nationwide fad, selling over a million units in its first year. Credit: @nbcnews | History In Pictures

Pet Rock Mania: The $1M Marketing Trick of 1975