That's NOT Chaga!
Chaga Mushrooms are in fact a white rot fungus attacking the heartwood of the tree. They can grow on many different species of trees in the forest and can easily be mistaken for other types of fungi or growth. Be wary of Fool's Chaga!
Corky Bark Disease - NOT Chaga Mushroom
Tree Burl - NOT Chaga Mushroom!
Tree Rot - NOT Chaga Mushroom
Tree Rot - NOT Chaga Mushroom
Fool's Chaga - NOT Chaga Mushroom
Cherry Tree Wound - NOT Chaga Mushroom
Strange Diseased Growths - NOT Chaga Mushroom
As you can see there are many different growths that can easily be mistaken for Chaga Mushroom. Be mindful of what you take from the forest and ensure that it is in fact the correct polypore fungus. If you are not sure - leave it be. Just like any forest mushroom use caution before you decide to ingest.