I know human biology and I know that the gall bladder uses bile to break down fats. The high fat meal of avocados stimulated the bile flow which pushed out all of those stones. Pretty common sense if you ask me. I saved a few of them and plan to take them to the doctor to see what he says.
Take the half inch ones and have him explain to you how they CANNOT physically pass through the bile ducts after he stops laughing.