metal sphere, but what is it?

[CCDAMEEK]

I am trying to find out what this sphere might be for a friend. It was found many years ago along the eastern coast of Florida, near Cape Canaveral.

The sphere is approximately 4" in diameter, has a seam in the middle and marks that makes me think that the two halves were pressed together.
There is a hole in one end that is filled with a hard material, that is now green. (copper maybe).
It is made of non-magnetic metal, and although dented, it is very hard.
And if you shake the item, it sounds like some kind of granules is inside, and mostly filled with them.
The sphere floats.

Any ideas??

 

[bradyboy]

a better close up of the green area would help
how is the green area attached
if the green area is of a brass alloy, may indicate it was exposed to a caustic material
I would then assume the ball is stainless
imo
brady