"The Tripods" trilogy of books features a central theme of invasion by alien-controlled tripods. It was mounted on wheeled mounts, tripods and armored vehicles. Floor stands are often tripods and telescoping. Sacrifices of horses, bronze tripods and huge cauldrons decorated with sirens, griffins etc. This included tripods that walked to and from Mount Olympus. To lengthen the line, ropes made of rawhide were placed over wheeled wooden tripods. Utensils were often held directly over the fire or placed into embers on tripods. For simple star trails, no additional equipment may be necessary other than common tripods. They could depict bowls and tripods, griffins, spinxes, and especially mythical figures and deities. This is not found on the more expensive photographic tripods. Bronze tripods and jewellery have also been discovered as dedications at archaic Olympia. The huge tripods appear to have been made to resemble the aliens themselves. There were many problems trying to create the walking tripods of Wells' novel. The tripods of Zhou dynasty may be the earliest prototypes of the hot pot.