8. Ancient Floor Game
A swamp in Mexico holds an artificial island that is 5,000 years old. Mostly made of discarded clam shells, it grew to such a size that the fisher folk who created it started using it as a food processing station. To prevent the shells from cutting their feet to ribbons, they laid clay floors. Holes in the platforms fit the pattern of wooden racks, perhaps used to dry fish.
The site of Tlacuachero also has other head-scratching holes nobody can fully explain. These oddities are arranged in ovals, are smaller, and dent specific areas of the floors. Decorated clay disks found at Tlacuachero hint that the workers could have played some sort of floor board game. If true, it could be the oldest clue to how the ancients amused themselves in the Americas.