RE: Fascinating polypores. / Faszinierende Baumpilze.
Hey @jaki01 ! I've been on vacation for last week or so and haven't been on steemit or chat much - but I'm returning tomorrow and decided to check in and saw that @lemouth had direct messaged me in discord this post. So, of course, I had to do a little sleuthing.
A lot of these woody polypores tend to grow on specific tree species. And of course seeing the underside clearly/getting a spore print would be further help along with some other details that might assist a more specific identification.
Having said that, based on these photos and your location - I'm assuming Europe - I think it is worth comparing what you found to Fomes fomentarius. That link leads to an American centric post on the species, which is found across the world. Wikipedia has a good section on it as well.
Some of your photos looks like it could be multiple species, or one species in different states of maturity. Another possibility worth comparing to Fomitopsis pinicola, specifically the picture with the redder edge.
If not these particular species, something within the Fomes genus seems likely. The inside of the caps can be used as tinder i think and tends to be very dry.
That's what I was able to come up with on mobile here in CA. Always happy to check out other mushroom pictures if you stumble upon any.