Zinc tends go soft like salt crystals,grey/white flaky bits,while its been eaten away the internals are being protected,changed mine on the diesel every 12 months where they needed it or not,same as the zinc on the shaft,may look fine but always changed.

Also to the above comments..
 The anoide is actually called a "sacrificial anode"
 Its made up of an alooy being aluminium, magnesuim , and a few other rather  'unstable , metals that will corode away ..
Thes more unstable metals corode before the metals of the engine start to..

 The "salt" is the 'rust' of these metals.. and unlike ir\on , the oxides are white powders that flake off very easy.. They flake/rub/ fall off easy so new sacrificial alloy is exposed all the time.

NEVER, NEVER do anything to stop prevent, cover seal, lubricate these, even accidentally spray crc or similar over them....
All that is needed is a rub or quick brush with a wire brush once in a while, and check  electrical continuity between the surface and the body (outboard case) to which they are attached.

ok, thanks fellas.so all is normal then. I replaced these a few months ago with new ones. though about a trying a flush bag to see if that makes a difference, but probably wont bother

My formula cleans it up i have the evidence in my motor I cleaned 8 of them .