Terrapins Shells

Question
I have two terrapins who's shell peeled but has not fallen off, is thin and seems to have shell underneath, its been like this for two years now. It looks worse when they dry in the sun. Should I scrub them off? Are there any supplements they can have or should be having.

Answer
Scrubbing them off is usually a bad idea.

Without more information, like species, sizes, habitat size and set up, temps, diet, etc., I cannot offer much of a guess as to what is happening.

One bit of generic advice is to use a good, reliable care site to review the needs for the species you have and then see how they compare to what you do.

A good site to review would be http://www.austinsturtlepage.com