My common Musk turtle's shell is....peeling?

Question

Okay I have two common musk turtles (Bubbles and Angel) that are about three years old. Now Bubbles shell is peeling. It looks kinda like a bad sunburn. Only the peeling doesn't come off. I think I may have an idea as to why its peeling but I'm not sure. Bubbles spends all her time sunning herself, while Angel unfortunately doesn't. Angel doesn't have any peeling on her shell. Do you think the cause of Bubbles peeling could be caused from dryness?

oh and another question. are my turtles still considered hatchlings?

Answer 1

 the only problem i have with your answer is.... my musk turtles dont touch veggies