Split and simplify the following sentence while retaining its full meaning: in architectural decoration small pieces of colored and iridescent shell have been used to create mosaics and inlays , which have been used to decorate walls , furniture and boxes .
 Simplified version:
in architectural decoration , small pieces of colored and iridescent shell have been used to create mosaics and inlays . these inlays have been used to decorate walls , furniture and boxes .