The RES I am rehabbing seems to have a massive ammount of shell damage. It doesn't seem like active rot; it isn't soft or peeling or stinky or otherwise messed up. However, his shell frankly looks like it barely survived a meteor shower. Both the top and the bottom are deeply, badly pocked. In some places the pocks are so deep that when cleaned out, you can see white beneath that I can only assume is bone. I'm keeping his water quality pristine and his actual body very clean, and on the suggestion of another rehabber have been putting some SSD cream on the spots where bone is exposed to make sure it isn't quite as susceptible to pathogens. But seriously, what even causes damage like this to the top AND bottom?
(The light areas are not all bone in this pic; this was upon arrival and he had quite a lot of dirt in the pock marks)