I assume you mean the cellular structure in the shell, and if so, it is not unusual that the shell is recrystallized, particularly by calcite or dolomite.  I don't see geopetal structure although one of the shells could have internal crystal precipitation (second photo, top part).  In geopetal structures you need to see sedimentary features like micrite (lime mud) settling by gravity inside a shell with a flat surface spanning the void space created by the shell showing which way is "up".