Question!

So I have some bladder stones from a dog and I would love to keep them preserved well. I have placed them in water but I think they’re breaking down. What could be the best way to keep them???

I thought wet specimen was one of the better ways but not with alcohol or formalin since they’re solid and I wanted to avoid having them break down. Although now after a few months I’m wondering if they should’ve been dried and then placed in an empty jar for safe keeping.