my 2 new briggs

i know i done it again, i had went to petsmart to get supplies and saw these in the tanks i hunted for the best shelled ones i could find,.. and the whitest one and the darkest one, not bad if i say so myself,..

and of course the royal gems, of Rachels stuck in between.. this is the first day i have gotten to see all 4 purple one i've gotten all at once,.. there were 2 under the ivory, and black, (as petsmarts calls them)

hey Rach, it is normal for them to have such a defined line across them where the new growth is,? some have it and some don't even my large ones do, some do some don't ad they are in the same tank with the same food???
sorry it just bugs me,.. seeing a line,..on such pretty snails,..