I think Tanmay is referring to the little pale squiggles under the keratin of the scales. It is not shell rot, but just how the scales form and develop. I don't have a better answer than that, but it is normal and will eventually disappear. (If that is indeed what you are asking about)
But, I agree with Tom. Provide a bit more information about how your tortoise is housed, and clearer answers can be given if needed.