Fomes fomentarius, aka more commonly referred to as the horse's hoof mushroom around here, is a parasitic mushroom that feeds primarily off of dying birch trees and stumps while leaving a thick white mycelium cluster in the wood (white wood rot look). This mushroom is very easy to find if you can find a dead birch tree... Covering them sometimes like a rock climber's dream wall in my opinion. 

Each year a new layer will form on the margin adding the ring like pattern of growth each year. Taking years to grow to a decent size, overharvesting of these mushrooms has made them a little bit tougher to find. From what we've read letting them grow for about 3 years is favorable. We here would love to set up more sections of downed trees for the mycelium to feast off of and we can continue to study this beautiful specimen with so many uses.