Download DazStudio,  in the folder contentruntimegeometriesprops,  you will find ball.obj, copy it into Poser's runtimegeometriesprops folder

Or create any sphere mesh with 0.05 radius, save it as wavefront obj with the name ball.obj

Don't worry about ball.obz, ball.obj will work with no problem. If you want exactly ball.obz compress ball.obj with gzip and save it as ball.obz

Poser's ball is a sphere with 266 vertices and 288 faces

 

Stupidity also evolves!