I have Nettie snails and I think their shells are eroding by the look at the pic below. They were somewhat eroded when I got them but I did pay attention to if they were eroding more since they always hide so I can’t see them often. But when I saw them it looked worse and I don’t want them getting any worse than it is. I am at the beach and I wanted to know if sea shells will increase the hardness. There is also oyster shells if those work better. I don’t really see any coral or else I would get that. Thanks! Also is that pink on the shell the inside of the snail? Also will it heal? Thanks again!