Good thoughts, Bill. However, I believe that actual stones are indeed passed in addition to soft, congealed cholesterol/bile balls.
I'm a newbie and just did my first flush. Several of the larger stones (large pea-sized) were extremely hard. I unsuccessfully tried to crush them with a pencil against the side of the tiolet bowl. There's no way they could have got that way overnight. The smaller ones broke up much easier, but they looked just like smaller versions of the hard stones. You just have to get "in there" and check them out to determine for yourself. I've recently learned that many here use a collander !