Help with Ancient Maya Offering Shells

[wolfi]

Hi, everyone!
Could it be possible for #1 to be Nerita tessellata because of the tiny teeth at the inner margin of the opening? As far as I remember, N. versicolor has more prominent teeth. But, anyway, they might be worn, too.
For me it´s difficult to make a decision between Cyphoma gibbosum and Cyphoma signatum, only on the basis of shell morphology. Are there some characteristic differences?
Kind regards: wolf