Cleaning of very crusted disc

[IronSpike]

I'm not sure this even is a coin. However I did break some of the crust off and it appears to be silver underneath with some kind of markings.

The object is in pretty bad shape and I reckon I can't do much harm to it valuewise

It was found in the ground (colonial site) and not in beach/water.

Any advise on how best to clean it would be appreciated.

[IronSpike]

Have posted some pictures in What Is It?

Have enjoyed your treads on various cleaning methods.

I used olive oil initial to soften crust. Then the saltwater/battery charger method and used baking soda between each dip. Baking soda applied rubbing disc with my fingers.

No harm done on this piece. It's not silver so likely not a coin/token either