Bladder stones, also known as vesical calculus, are crystalized minerals that form in the bladder when urine is not completely emptied. These stones will often pass when they are very are very small in size, but can also get stuck to the walls of the bladder or ureter, gradually collect mineral crystals, and grow in size. As they do, they can cause a patient to have problems with urination, as well as a great deal or pain and discomfort.