Dry shell?

[Bear2023]

For the past week and a half my three toed box turtle has had something white on her shell can anyone tell me what it is? Is it dry? What should I do? I have a few photos:

 

[Bear2023]

Sorry if there not very clear

 

[Sarah2020]

I think it's new growth or calcium in the water is finding the scute edges. His face does look dry so check setup. I would get some coconut oil and gently rub on the shell this has added benefit to really show of the shell as well as moisturise like we use cream .