 After the casting of cash coins had shifted to using bronze moulds these coins would appear as if they were branches of a "coin tree" (錢樹) where they had to be broken off, all excess copper-alloy had to be manually chiseled or filed off from the central holes.It is suspected that the "flower holes" and "turtle shell holes" were produced during chiseling process, presumably while the employee of the manufacturing mint was doing the final details of the cash coins.As manually filing and chiseling cash coins was both an additional expense as well as time-consuming it is likely that the creation of "flower holes" and "turtle shell holes" was ordered by the manufacturer.