I pulled last falls fan out of the freezer to try to mount it myself, it was a young bird. I decided to remove each individual feather and have it arranged in order in styrofoam. There were several feathers that weren't hollow, they were soft around the last inch of the base and filled with pulp/blood and were kind of black and had a tubular sheath going up toward the feather. Are these still ok for mounting? Is this because the feathers were still growing?