It is neither plume or mold. What you are actually seeing is a growing civilization upon your crumble cake. Microscopic people are building and creating. What you see is quite small, but to them they are towering buildings, skyscrapers! An entire world much like our own is being developed and even thriving on your tobacco. There is industrialization, agriculture, technologies... people going to and from work, tiny children going to and from school, playing sports, everything we do upon our own world is being done there. And you are their god. They see you looking down on them and turning their world over and over, observing. And when you reach down and break off a piece of their world, setting it aflame, they know that they have greatly angered you.