Those look like liver flukes to me - young adults. The older ones are much darker and bigger. These young ones were not big enough to become really "attached" in the liver - so they were flushed out along with your stones. Liver fluke larvae look like small white balls. The younger the fluke - the lighter in color it will be - the older - the darker. This is from them becoming stained with blood and bile in the liver. Good job!