Thanks - great links, especially the article on gall stone pathogenesis. This is excerpeted from that article:
"Primary bile duct stones are stones formed in the biliary tree as the result of bile stasis, e.g. above a stricture, around foreign material such as a suture, or in association with infection. They are often earthy, muddy stones that can reach large dimensions, and are composed predominantly of calcium bilirubinate and minor amounts of cholesterol or fatty acids. These stones do not dissolve well in lipid solvents and may be found in the intrahepatic or extrahepatic bile ducts."
This completely corresponds with my flush. The last few rounds of stones that I passed included translucent red stones, litte red worms (up to 3/8") and stones embedded with worms. These were followed by a gross looking cigar shaped stone approximately 3/4" of an inch which matches the "earthy, muddy stones that can reach large dimensions" description. It seems like these worms and related embedded stones acted as net in the biliary tree, blocking the particular tube and causing the cigar shaped stone's formation. It's cool the way my flush matches this description.