Artist's conk is exceptionally common in Maine. Growing on older sugar maples and many other hardwood trees usually persisting for years. When they are picked the interior reveals layers of pores that are like rings on a tree in describing age. 
Artists use these mushrooms for etched designs when fresh and for landscape and other painting when dried. They can be displayed differently than most paintings because the mushroom will stand on it's edge on a table or shelf. They become almost as hard as a block of wood and will last for many years.
There is some scientific evidence that indicates this mushroom has  some antibacterial properties. Artist's conk is inedible as food but can be made into a tea or tincture. Artist's conk contains polysaccharides and triterpenoids that have various medicinal implications. They can be made into a medicinal tea by drying them thoroughly and grinding them with a meat grinder or other type of grinder.