I had the *same* thing happen. And as gross as it sounds, these things looked like almond roca a bit. right in the middle of the flush and then they popped out. Diarreah,... diarreah,... plunk plunk plunk...what the...?
Mine were slightly smaller than golf balls but still really large. I counted about 6 of them. I did have to exert a bit more effort to get them out at the end as they were so big, but it wasn't a big deal.
I am sure they are from the liver and seem like just a coagulation of liver chaff and stones. I didn't cut mine open but I also had a liver fluke come out, dead, encrusted with what looked like the same sort of stuff.