Hello Forum, Please excuse me if I get this completely wrong, my first forum posting EVER !. I need some help in identifying the Lichen / fungi / lifeform ! shown in the attached photo (hopefully). The growth is multiple (as shown) is relatively flat, circular and yellow with white borders . They were found growing inside a 1000 year old Oak tree with a hollowed stem base / lower trunk. The heartwood decay beleived to be the causel agent is Laetiporus. The decayed wood is dry, reddish brown. By the way please ignore my hair and forehead !. I need to provide some recommendations with regards for the management of the tree and its associated lifeforms and would really like to know what type of lifeform this is (fungi, lichen, liverwort ?) trees are my speciality, things like this are not. Any help would be greatly appreciated. Thanks in advance.