This is a Spalted Oak Bowl, 8" x 3.75". It's a piece of wood that was given to me that came from Pensacola Florida. It was the first time I've turned spalted, punky wood. On one edge of the bowl the wood kept tearing off in pretty big pieces, much more than normal tear out. When I tried to sand it out, it was so soft that it flattened that edge a little, even while sanding with the lathe turning. Finished with tung oil and briwax.
You might want to add some kind of stabilizer or wood hardener to the punky spots next time, before you sand. Maybe even before you turn. I've had the same experience with sanding the soft areas. Sanding sealer, shellac, CA glue, and a number of other treatments can help stiffen things up a bit and make the spalting easier to manage. Good luck.