I have had rounded grains of reddish-orange sand in my urine for over a year. It's painless and they are there in ones and threes, or dozens, hundreds at a time, about once every sixth or eighth time I urinate. The Urologist tells me they are not kidney stones, but at bladder stones, and common, but I can't find a single word about them on the internet (regarding humans). They seem to be mentioned in cats and perhaps goats, and remedied by changes in diet.