Spotting

Thank you! :)
I added a photo of the underside :)

I was also thinking about H. annosum, but they come in so many shapes and sizes, so I'm confused :D
I tried to get some spores too, but I guess it was too old.. I read that when H.annosom becomes old, the underside becomes a bit yellowish, and this has a bit yellowish underside :)
Now I will have to read a bit more about your other suggestion! :) Thank you! :)

Nice finding Sintija,could be a Heterobasidion annosum or also Fomitopsis pinicola,you dont have photos of the pores?that would help :-)