From time to time you may experience problems with your snails. Very little is known about what these illnesses are, what causes them, and even less is known about treatments. Unfortunately it seems more time is spent on increasingly more ingenious ways to kill them.
Because of this, the following information is a mix of whatever research is possible and available, theory and hypothesis, logical thinking and the result of various discussions with a large group of snail owners. It is with the help of the community at large, that these problems can at least be documented. Where possible I have tried to link to example incidents.
Hopefully, we can find some effective solutions to the majority of these problems but for now I'm afraid you'll have to be content with various suggestions and discussion.
The first thing to do is ascertain whether the break has occurred from an accident such as a fall. If this is the case then see Broken/Chipped Shell for advice on repair.
If the cracks or splits have appeared naturally through growth then it could be due to overfeeding or overly fast growth. This deformity may come under Bad Shell Growth, so check here also.
The pictures below illustrate the phenomenon. In one case (Fig. 1), the snail was kept on its own, free of other snails or objects that could harm the shell. The interesting point is that it was fed a diet particularly high in chicken mash, a mix of wheat and other cereals. It is high in protein and it seems possible that the snail was growing too fast and split the shell slightly. Shells are easy to break from the inside than the outside. If the snail hadn't been kept in these conditions the natural assumption would be an accident, as I have seen similar damage on larger snails, perhaps more severely which seem to have been caused by a previous accident.