On dead trees you can easily find Trametes versicolor also known as Coriolus versicolor and Polyporus versicolor.
They exist under different colors. Due to its resembling multiple colors in the tail of wild turkey, T. versicolor is commonly called turkey tail.
Older specimens, such as the one pictured, can have zones with green algae growing on them, thus appearing green.
T. versicolor contains a range of immunologically active polysaccharides. Human pilot studies indicate they might reduce cancer recurrence. Other basic research demonstrated that the mushroom inhibited certain human cancer cell lines in vitro.