What is the difference between heating a flat-bottomed beaker with a piece of iron instead of a stonewool mesh? Why is it important to explicitly use stone wool mesh in chemistry?

In heating a flat-bottomed beaker, the most important thing is to make the bottom of the beaker evenly heated, and because Asbestos consists of bundles of fibers, and the bundles of fibers are composed of very long and very fine fibers that can be separated from each other. Asbestos is highly fire-resistant, electrically insulating and thermally insulating, making it an important fireproofing, insulating and thermal insulation material. Asbestos mesh has such functions.

If iron sheets are used, there is a risk of serious consequences such as the beaker blowing up (because it is equivalent to heating the beaker directly)

It is imperative that iron sheets are not used instead of asbestos mesh