Really unhealthy shells

[Cohenjl13]

So I have what started as 3 and is now 6+ rabbit snails and rabbit snail babies. The older ones shells are getting extremely unhealthy though and I don’t know why. It’s all of them even a younger one is having calcium issues. I add about a cup of crushed coral in every couple months so they can munch on that and I also have a chunk of cuddle bone ya eat side of the tank. Any ideas what’s wrong before they die?

PS the little white spots on him are Nerite snail eggs, is just the end of his decaying shell I’m worried about

 

[shellyx]

I've kept and bred rabbit snails for years and mine end up the same. Like you ive added calcium and fed calcium rich food but their shells still go that way. Ive just put it down to the fact they are having to drag the shell around all day and it just wears. Hasn't caused any issues for mine i have 3-4 year old ones still going strong in my tank!