I am using organic potting soil mixed with coconut coir and the white flecks were in the soil. They aren't actually balls just bits of some organic material in the potting soil. Perhaps bone meal...not sure.
They are not actually so noticeable but brought out more by the flash of my phone camera.
(Just make sure they are not tiny pieces of Perlite or Vermiculite, used to improve drainage in soils. Some torts will eat these and there is a risk of bowel impaction.)
But your tortoise is cute, and the rest of the enclosure (nice depth to substrate, tall sides, pavers for basking; looks great!