That's beautiful Brunni Was it a wild snail? I'm wondering because the dark bands show periods of inactivity, yet at other times it seems to indicate that food was plentiful and conditions were just right. It looks to me as if it went through seasonal estivation.
It's a wild one. You are very observant ! The dark bands are in the shell's skin ( periostracum ), not in the shell itself which is white underneath the bands. They can probably related to months of rainfall/growth and periods of hibernation or aestivation/drought ( much like scientists examine growth rings in tree trunks to see years of regular or stunted growth ). Probably in an artificial environment ( i.e. cb GALS ) this feature is absent ?