I've got an oak tree. Within the last 2-3 weeks I've observed two growths on the base of the tree that started from nothing to what you see below. They're a fungus or mushroom of some sort. They're solid structures, but if you look closely you can see fuzz on the tree itself where they meet.
My plan was to call someone on Monday, but I'm not entirely sure who. An arborist? Before I do call though, I'm trying to get as much information on this as I can, because I know it can range from being treatable to being dangerous.
Any ideas? Thanks!