Kidney Stones: Causes, Symptoms, Treatment Options, and Prevention Tips Kidney stones are hard, crystal-like masses that form from minerals, acids, and salts inside the urinary tract. They may be very small, like a grain of sand, or rarely, larger than a golf ball. They are also called renal calculi or nephrolithiasis. Many small stones pass through urine on their own, but larger stones may get stuck in the ureter, block urine flow, cause severe pain, bleeding, or affect kidney function. Some stones may take up to three weeks to pass naturally. Read this: https://clearmedi.in/blog/kidney-stones-causes-symptoms-treatment-prevention