This fungi is very common- especially on oak. Chicken of the woods and beefstake fungus are the
most common cause of brown rot in oak trees.
Apart from oak, I have seen it on beech, apple, willow and yew.
It is a very distinct annual fungus, easy to spot as it is bright yellow. Chicken of the woods
forms many layers of sulphur yellow layers and is soft. It is edible and reputedly very good to eat.
It remains for a few months in a white, calcareous state.