Sorry, I never got around to taking pictures of shell disease. Next time I have and O.s. with shell disease, I'll try to get come close-ups of it. (Hopefully, that won't be any time soon.) One of the G. chiragra used in "Fastest Claw" had it, if you have access to that program.
There may be different "shell" diseases in different species. Hemisquilla frequently get a black shell rot. O. scyllarus get the rusty brown lesions that appear to start out as a bacterial infection.
If the ulceration does not penetrate the newly forming cuticle, animals do heal. Usually you will see some discoloration and perhaps some "bumpiness", but that will clear up during the second molt.
As I have said before, there is some danger of this disease spreading from on animal to another, but the use of a uv fliter can greatly reduce the this.
Roy