Decaying wood from fallen trees makes a superb micro-habitat for various forms of wildlife and that is why, on nature reserves at least, fallen trees are usually left to rot away naturally. If they fall across paths or present some form of danger then they have to be removed of course. One of the key players in the rotting process is fungi and many-zoned polypore (Trametes versicolor) is one of the most common. Bracket fungi are similar in many ways to the normal 'umbrella' toadstools, it is just that the fruiting head has a half moon shape. The fungus is, of course, present all year round. It lives within the log feeding on the decaying matter and hastening the recycling process. If you pick away at a rotting stump you might well find the white thin strands of the fungus itself. In autumn (usually, not always) the fruiting head appears which has a protective covering on the top and it is from underneath the spores are released.
Many-zoned polypore is probably the most common of the bracket fungi and occurs on virtually all forms of decaying wood. Some species, such as the birch polypore are more specialised. Trametes versicolor will vary in colour depending on the fruiting body's age, it dries out after serving its purpose and becomes harder and darker. When the fruiting body is fresh, however, it has this lovely 'concentric ringed appearance' with iridescent shades of grey, green, brown, violet and even black. This patterned effect gives its other name, the turkey tail fungus
It is not worth trying to eat it to be honest!