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.
Kidney stones can vary in size from the size of a tiny pebble, and up to and bigger than the size of an English pea. The larger kidney stones are too big to exit the kidney,â¦ and the smaller ones pass through the urinary tract with more ease.