what is this?

hi,
i did a flush last night. I got a lot of stuff, nothing too big,though.
however, something came out of me that i am convinced is from my liver or gallbladder because it is encrusted with that stuff, in fact i couldn't rinse or scrape it off.
it is longer than a penny and has the shape and color of a good sized new york city cockroach, but it is very thick and tough. the underneath side must have been soft because it is just like an empty shell. i have not eaten anything which resembles this and i wonder if there is a critter that lives in the liver that might fit this description. it is rather alarming.
thanks,
cyclo