Chinese freshwater mussels were once grafted up to 50 times per shell, or 25 times per valve. This practice was common when the industry mussel was primarily the cockscomb pearl mussel (Cristaria plicata). This mussel produced a high volume of low-quality pearls that came to be known as "Rice Krispie pearls" in the 1970s and 1980s. More than a decade ago the freshwater pearl industry of China shifted production from the cockscomb pearl mussel to the triangle shell mussel (Hyriopsis cumingii). The triangle shell produced fewer pearls, accepting only 12-16 grafts per valve for a total production of 24 to 32 pearls, but produced pearls of better quality.