The diagrams illustrate three development phases of a simple cooking equipment, from a basic stone to a complex structure.
Overall, the tool underwent significant development over the period. Once the equipment consisted of only basic parts, but over time it became more functional and useful.
In the initial stage, the equipment was composed of a single basic stone and a vase, without any protection for fire. Thus, the relatively simple design offered limited functionality.
In the second stage, the stone base was surrounded by a clay shield, and a hole was added to insert fuel. This version is also quite simple but more efficient than its predecessor.
In the final version, the equipment included upper and lower sections. While the lower section was covered by a metal and included a door for adding fuel, the upper section was a suitable surface where a pot can be placed.