100_0255

100_0255

Observation - 100_0255. Description: I have just noticed this fungal growth today at the base of the oak tree at the bottom of my garden. It measures 13 across. I'm keen to find out what it is and especially if it is damaging to the tree as this oak is a large one and could cause considerab

I have just noticed this fungal growth today at the base of the oak tree at the bottom of my garden. It measures 13" across. I'm keen to find out what it is and especially if it is damaging to the tree as this oak is a large one and could cause considerable damage to my own and neighbouring properties if it came down in a storm.
Update August 19th: I have added a close-up photo to help confirm identification as requested.