Very round Birch Bracket on fallen berch tree, Heeswijk-Dinther, Netherlands.

''Fomitopsis betulina'', commonly known as the birch polypore, birch bracket, or razor strop, is one of the most common polyporous bracket fungi and, as the name suggests, grows almost exclusively on birch trees. The brackets burst out from the bark of the tree, and these fruiting bodies can last for more than a year.