Having intermittent pain in lower abdomen. What are the chunks in urine?

I have been having intermittent pain in my lower abdomen for months. Presently waiting for an ultrasound appt. The pain is almost constant now, but seems to come in waves. Today I peed into a jar and found tiny white chunks at the bottom of the jar. The are solid looking and about the size of 1/3 piece of rice. Urine is good colour, but a little cloudy. I tried to examine things in my urine with upside-down binoculars and the particles that are floating look clear, fat at one end, sort of tapering down to the other end. It does not hurt or burn when I pee.