The term 'STUFF IN A PETRI DISH' can be summarized as a type of laboratory experiment involving the use of AGAR, which is a gelatinous substance derived from algae. AGAR is commonly used in microbiology experiments to provide a solid surface for the growth of microorganisms, such as bacteria and fungi. It is also used to culture cells in a Petri dish, which is a shallow, circular glass dish with a lid. The lid is used to prevent contamination of the sample and to maintain a sterile environment. By placing the sample on the AGAR-filled Petri dish, scientists can observe the growth of the microorganisms over time.