Large, shelf fungus growing on a dead, fallen oak tree in Lee County, Alabama, USA. Underside had yellow pores/tubes, eventually growing black hair-like tufts/spines? Top of fungus is white to yellow with black or dark brown velvety edges. There is a cross-section photo, but the lighting and quality is bad due to sun going down.
Spongipellis pachyodon (Irpiciporus pachyodon)
Marshmallow Polypore
8 feet in the are on a tree