Odd fungal growths on Red Oak stump in Fern Valley

All the gardeners know this tree; it lived just alongside the service trail to the Fern Valley pond and on those rare occasions when we drove to the pond, we navigated carefully through the section of trail narrowed by the base of this ~200 year old tree. I know I'll miss it.

The fruiting bodies of the fungus clearly demarcate the boundary between heartwood and sapwood. The tree has only been cut a week so the fungus has gone from a mycelial to a fruiting stage fairly rapidly and apparently as a response to exposure to air. It seems likely that the fungus would have eventually manifested itself as either a canker or a "bracket". If this were a White Oak, I'd think Strumella and possibly it is anyway.