Textured sphere are used to create patterns on clay by adding a little pressure and rolling where you want the desired pattern.
 
        Sizes                                         Price
Large = ~2.5in Dia                    $20.00
Small = ~1.25in Dia                  $10.00
 
Pattern Names:
Rapids
Waterway
Icy
Hexen
Petals In
Buckshot
 
These textured spheres where design by Pete Johnson.  Pete is a great guy and I  reached an agreement with him to be able to sell these exclusive in my shop.  I found Pete on Printables.com, if you are looking for some STL files check him out.
https://www.printables.com/social/5804-petej/about