Fordite, also known as "Detroit agate" or "motor agate," is a unique by-product of the automobile industry. It's not a naturally occurring stone; instead, fordite is made up of many layers of automotive paint that have hardened over time. This material is typically found in the paint booths of auto factories, where cars were spray-painted by hand. As the paint sprayed over vehicles, excess paint would build up on the equipment and surfaces around the painting area. Over the years, these layers of paint would harden, creating colorful, agate-like structures.