Snails growing dark shell?

[SweetTart]

I just bought 3 snails for my 10 gallon tank. Two nerites and one Japanese trapdoor.
I've had them in the tank for 2 days and have noticed all of them have dark new shell growth.

Is this bad? Are the shells growing too thin?

Water parameters:
Ph: 7
Ammonia: 0
Nitrites: 0
Nitrates: 0.2 ish
Kh: 35.8
Temp: 80

My baby horned nerite

And the Japanese trapdoor

 

[Demeter32]

Don't worry, the edges should always be dark as that is the point of new growth.

 

[SweetTart]

@Demeter32
Okay, thank you! I was a bit alarmed because the color looked so different, good to know that's just normal growth.