Mystery snail normal shell growth?

[Maddie Dalsing]

I got this blue about a week ago, when I picked him out he didn’t have that dark blue growth, in the picture it shows his light blue shell that ends in the line with a slight crook, when I got him that was the very beginning of his shell, I picked him because he had a slight crook on his shell edge right above his head, but now it’s grown towards the back and has the darker blue edge, I guess I want to make sure it’s normal growing

 

[Maddie Dalsing]

I got this blue about a week ago, when I picked him out he didn’t have that dark blue growth, in the picture it shows his light blue shell that ends in the line with a slight crook, when I got him that was the very beginning of his shell, I picked him because he had a slight crook on his shell edge right above his head, but now it’s grown towards the back and has the darker blue edge, I guess I want to make sure it’s normal growing

When I first got him

 

[LarsB]

I speculate that your environment, including water and food, is an improvement over the same things/water parameters he was raised/born into. The change in water condition will cause snails to develop ripples and ridges in the shell, as well as color changes as they grow and age. You can often see where the changes happen by the extremity of those ridges, but each animal is going to be different.