Platyhelminthes are also known as flatworms because they are worms with a flat body. This is the main external morphological feature that differentiates them from nematodes (roundworms).
Even though 85 percent of kidney stones are small enough to pass during urination, fewer than 50 percent of patients chose this option. A person with a normal-size ureter can usually pass a kidney stone with a diameter less than 5 mm (about 3/16 of an inch) without significant pain or risk of kidney damage.
Few hours to days: How long it will take to pass a 1 mm stone depends on the location of the stone, size of the stone.1mm stone will pass faster and with ease than a larger stone. Imm stone can take few hours to days to pass.