Here is a photo of "worms" on the bottom bracket of the same bike posted by [MENTION=425004]merziac[/MENTION] before paint removal.



In this case the rust was only under the film as described by [MENTION=452523]machinist42[/MENTION] above. As you can see by the photos posted by merziac some of the heaviest rust was at the top of the seat lug, an area where it was easy to see that they had not propagated from the inside out. I see these fairly often in the coastal environment where I live.
Brent