The ARK (also spelled Ark) is a barrel attachment found in the Extinction maps Awakening and Exodus. It allows weapons to turn into a laser weapon, though it still uses conventional ammunition and also has the additional effect of causing extra damage to cryptids, which further makes any that are killed with the weapon it's attached to explode in a similar fashion as to the Pipe Bombs.
A kidney, ureter, and bladder (KUB) study is an X-ray study that allows your doctor to assess the organs of your urinary and gastrointestinal systems. Doctors can use it to help them diagnose urinary disorders and causes of abdominal pain.
Kidneys and Protein. Kidneys are bean-shaped organs in your lower back -- one is on your right side and one is on your left. Nephrons are structures inside each kidney that contain tiny tubes called glomeruli. These glomeruli are responsible for filtering your blood to remove waste products and fluid to produce urine. Kidney damage allows protein to pass through the glomeruli and move into your urine.