2 inch anode ball.
An example of the element Cadmium

It is almost certainly used in electroplating, where the anode often consists of a cloth bag containing balls of metal or shot, depending upon the exact coating required. I'm not an expert on the subject, but my late father and I have worked in plating factories in the past and seen this in action. I believe this is done to provide a larger surface area, whilst the cloth bag prevents particles of the disintegrating anode from detaching and adhering to the article being plated.
From memory, nickel-cadmium plating used to be used on engine parts and other high-wear, high-temperature items, but I know this was banned in the UK some time ago (I'm not sure about its current status in other parts of the world). I believe it was replaced with zinc-nickel, but couldn't say for sure.