Shell getting dark spots.

[Turbo969696]

Hello,

This is my 14 year old sulcuta - Turbo. His shell has started getting dark spots. I first thought he got some mud on his shell but after bathing him, dark spots did not go away. Is this something I should worry about?

Please advise,

 

[Turbo969696]

Here is a picture. Middle of his shell is getting darker. His tail end was his original yellowish brown.

 

[Ray--Opo]

Everything looks fine to me.
I have seen old sulcata's that most of their yellowish color is gone from scutes.
The brown separating the scutes is growth lines.
Are you talking about some dark brown is getting wider and darkening the edges of a few scutes?
It all looks normal to me.
How much does Turbo weigh?