Mystery snail shells green, help?

My three mystery snail shells look like they have algae growing in the lines and I’ve used a toothbrush and it’s really on them.
Is there a way to get them clean and pristine again?
I do use calcium supplements in the tank
Cuttlebone, calcium liquid, blanched zucchini sometimes and algae wafers

Hi and welcome to the forum

It's just algae so I wouldn't bother trying to clean it off. It's camouflage for them

But how does PetSmart and other fish businesses keep their snails completely algae free?

Put them in a tank without light and the algae dies off. Have lots of snails in the tank and they crawl over each other and clean the algae off their shells.

Maddie Dalsing said:

But how does PetSmart and other fish businesses keep their snails completely algae free?

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My guess is they have them there at the store for only a short time before selling them. I had two golden mystery snails and I have seen them go over the each others shell. I wasn't sure if they were cleaning or mating. I have now separated them since they were attacking my plants. I bought them 2 months or so ago from Petco and no algae on them so far. Have you looked on-line for how to safely clean them? That or try what Colon_T said.

I think they look really cute with the algae lines, gives them a real rustic look

I have 3 little bristle noses in my plant tank with have MS and MTS. They love giving them a quick clean over in their travels around the tank throughout the day.