Is this a Nerite or Mystery ?

[RiDaPe]

I got this snail from the pet store last week. I went in asking for a Nerite. The girl working there didn't know what she was doing and the tank had many different kinds of snails in it. Can anyone tell me what kind of snail it is, and if the lines on the shell are anything I should be concerned about?
Thanks!

 

[SaraB]

Kind of looks like you got a black mystery snail. Mystery snails are fun to watch. They like to climb to the top of the tank and free fall back down.

 

[earhtmother]

The lines are *growing* marks, where the new shell has started from old