Old fulicas and their shells

[samurai]

My old fulicas has grown this weird black edge on their shells:
picasaweb.google.fi/hette00/Achatina/photo#5172735375825639218

It grew soon after they stopped growing. I´ve never seen something like this in any pictures of fulicas...

[spook]

That looks fairly normal to me.....it's the lip of muscle holding them in their shell.....they obviously have fairly dark skin that's all..