Passing lots of these things - what are they?

Have had back pain lower right and right lower abdo and pain, it’s 100% a stone, have passed a few - got apt with urologist and referred for CT and internal camera up the you know what. Still sore, trying to drink as much as possible, lemon water, could there be a big one or likely a lot of smaller ones like this? I think it’s a uric acid type. Have many people had these and what’s the prognosis for removal like? Wondering they’re fragments of something bigger.