Most individuals of our favorite land snail Eobania vermiculata have shells with 5 bands, although some of which may be fused into wider bands.
One may occasionally come across shells that are devoid of bands. In the picture below the shell on the left is the usual variety, while the one on the right is "bandless".
Presumably, the bandless shells form when all the bands merge to create one diffuse pattern. Here is another example.