We’ve come a long way since humans started walking upright around 7 million years ago. You have the invention of stone tools in Ethiopia about 2.6 million years ago. The discovery of fire some years after. The creation of papyrus (ancient paper) in ancient Egypt and then soap a while later.

Many inventions have changed our lives for the better. Like the printing press, the wheel, electricity, the telephone, computers, the internet, cars, planes, and even space travel. But there have also been a few very questionable, and pretty useless, creations along the way.

In 1975, a guy named Gary Dahl brought us something known as a pet rock. It was nothing more than a rock with two eyes, sold in a cardboard box and nestled on a bed of straw. Yet, it took the world by storm. Millions of people rushed out to get one. It came with an owner's manual and a 32-page instruction booklet on how to care for your new "pet".

“Your PET ROCK will be a devoted friend and companion for many years to come,” read the booklet, adding that “Rocks enjoy a rather long life span, so the two of you will never have to part –– at least not on your PET ROCK’s account. Once you have transcended the awkward training stage, your rock will mature into a faithful, obedient, loving pet with but one purpose in life –– to be at your side when you want it to, and to go lie down when you don’t.”

By the following February, Dahl had become a millionaire. He had sold over 1 million Pet Rocks for $3.95 each, proving that the world is indeed a very strange place.

As if that wasn't weird enough, the 2000s saw the introduction of the USB Pet Rock. Again, nothing more than a rock. But this time, with an added addition of a USB cable that you could plug into your computer. And what did it do when plugged in? Absolutely nothing. Here is how one retailer advertised the "innovation":

"Simply plug the USB cable into a free port and let the fun begin. The USB Pet Rock will instantly begin to work its magic. People will stop by and ask you what your USB Pet Rock does. Each time, you can make up a new story. For no matter what you say, it will be greater than the truth - because these USB Pet Rocks don't do a dang thing. Except make you smile. And confuse your friends and coworkers, which will make you smile even more. So, get your USB Pet Rock today, and help make us rich tomorrow."

Also in the 2000s, a man by the name of Mike Madden found himself facing a major dilemma ... Or so he believed. His two pet goldfish, Malcolm and Ethel, did nothing all day, but swim in circles in their bowl in the confines of Madden's home. Their owner worried they weren't going for "walks" and weren't seeing enough of the outside world. So, he devised a plan and invented a Goldfish Walker. We kid you not.

“If a fish is in a bowl on a shelf swimming in circles, it must get bored. I decided it would be fun to take it out with me down to the pub," said Madden, who was featured in several publications after being spotted "walking" his fish.

Madden later claimed that his one goldfish Malcolm lived to the ripe age of 11 years, because of his adventurous lifestyle, "which included trips to the pub and walks around town," reported The Mirror.