My belief is that the spirit that is around is impressed upon the environment, be it tree, cloud, fabric, plastic. I have had many more experiences of this lately (and more swamis, too!), followed by interactions with the spirit or finding clues that validate that what I am seeing is more than mere fancy. Not to say that these spirits (i.e., swamis) are trying to be seen, that I do not know, but the strength of their presence is visible to the viewer who would see them, in this way (seeing the impression in material) if that is the will of the viewer.