Problem with a lot of these parasites is they attach themselves to the wall of your intestines where they quit often stay when they are killed by the parasite herbs. They are then broken down and dont really come out as much that is recognisable as a parasite. But when they break down they release the bacteria and viruses within them into you digestive tract where they can make you feel a little rough for a while, and give you a bit of a belly ache.
As for what these rice things are, they maybee small life stages of flat worms, like the human intestinal fluke, or maybee something to do with tapeworms, dont really know. The problem with eggs is they are so small you shouldnt be able to see them, roundworms produce 200,000 microscopic eggs a day.
Who knows, there are so many different types of parasites, in so many different shapes and sizes, these rice things probably are parasites.