Found during Scupper Replacement - Anyone Know What It Is?

[Scuba_ref]

I am in the process of replacing my scupper with the stainless steel version (plastic one was rock solid btw) and I found what looks like a cap or plug, although it seems a little shallow to be a plug. I found this right next to the drain hole (not in the section by the scupper) so it could have washed in from another part of the boat. Does anyone have an idea of what this might be? It isn't very big, that is a quarter next to it for perspective.

Also, I noticed this last year (we bought the boat in July) and had made a mental note to look at it if I ever got inside...the female section of the drain plug, the part that stays in the boat when you remove the plug is loose. When I put the drain plug in or take it out the little bit of pressure with the wrench causes that piece to move. Has anyone reinforced that piece? If so how?

Thanks,
Stefan

 

[CrankyGypsy]

plug on the head cover between the spark plugs. I have one that won't stay in.