Tests positive for silver content any ideas on what it is?

[spentcattle]

Found this on a beach today. At first I thought it was one of those aluminum net floats but it isnt rounded at both ends. Does test positive for silver content which I believe aluminum wouldnt.

 

[DMN]

I suppose you could weight it as well. I imagine it should have some pretty good mass if it was silver. Is that some kind of lid on it? Perhaps there is something inside?