The given diagrams illustrate the changes of cooking equiment by three specific images.
Overall, the latest tool is much more complicated than the two previous.
The ancient cooking equipment has a shape of flower vase with stone around its bottom to put it on. Then the wood is fired at the middle of the stones and bottom of the vase. Next, it is changed into a shorter and smaller clay shield which has a big round mouth compared to the old one. Therefore, users can see directly the charcoal and burned wood. Last but not least, cooking equipment is developed into a shape of a big bowl with many extras like grate for charcoal, clay lining, support for pot and handle around the bowl. Moreover, it goes with a metal thing below with a door which is opend to remove the ash and air inside and closed to cook.
