This fungus looks like half of a old pear shaped puffball slapped onto the side of a tree. They grow on dead wood similar to pear shaped puffballs, but these are found in spring, rather than later in the summer. They start out more round but as the spores mature, the surface becomes papery and begins to look more like a blister of some kind, rather than a ball. Inside the papery skin which will eventually break open, are an abundant mass of brown spores which will take to the sky as the wind blows by.
