Painted here are mushrooms, a buttress root of a rainforest tree and the decaying leaves of the forest floor. However the decay is not destruction, it is the generation of new life, materials and energy which are drawn up by growing things. This new life energy is portrayed through the painted leadlight effect, giving the forest floor a luminous vibrance as the energy is drawn to the tree.
N.B I don’t mean spiritual energy in any sense. As an atheist, it would be sacrilege to suggest such a thing… Oh, hang on, no it wouldn’t. (I don’t believe in religion, therefore I don’t believe in sacriligion).