Thanks Telman! I really appreciate the humility and conscientiousness in your reply. I will check out with a gastroenterologist. Knowing your suggestions, I'll now have some pointers - I was a little dismayed when the primary health doctor had no idea what the item was, but your insight makes sense and I'm sure a gastro specialist would go further in that direction.
Your question about pain is really insightful. No, in general lately (ie, the past several months) I'm strong and in good spirits, have good digestion, no abdominal pain - but this is after a long journey of finding the right balance, when I'm not in balance the digestion is where it all goes wrong. I know my mom used to get diverticulitis attacks, and I sense that my intestines just react fast to a confluence of things, but also recover fast.
There's a couple of changes two weeks ago that could have thrown me off balance- an episode of stress overeating and giving up caffeinated tea (habitually had with lots of lemon), within a week of each other. Perhaps that threw my bile or gut off balance and it's time to find it again. I did have abdominal pain when the first enterolith passed, and it was very surprising, I thought I perhaps ate bad fish, but perhaps my gut got angry at some of those things. I'm considering all this an early warning sign. Maybe I'll try undoing some of those changes slowly (like re-introducing the tea and maybe then tapering off while using other bile-promoting foods like more strong herbal teas), and being more aware about eating during stress. Maybe later on I'll start some of the liver flushes, when thing seem more stable.
One random question - I was reading a pubmed article about enteroliths, and it said (I think it was a gastroenterology radiology book) said that enteroliths can hang out in the gut for even years and aren't passed. Maybe you have no idea, but just curious - do you think a big smooth one, very oval and soft white precipitated bile-salts inside, could be years old? An old thing would calcify maybe, no? No worries if you don't know, I'll be asking docs too!
Thanks again Telman, so great to have your perspective!