Most best friends have something in common — but these cute cats have taken their friendship to a new level by sharing an internal organ.

The friendly felines bonded after the gray cat donated his kidney to 2-year-old Arthur, who was suffering from a fatal kidney disease, according to Caters News Agency.

Joey, the tabby, was adopted by Fred Petrick and Tony Lacari shortly after the procedure, which cost $5,000.

Now the two cats are inseparable — constantly curling up together throughout their Virginia home.