Found this in my bilge...anyone know what it is?

[Uncle Binky]

I discovered that my bait tank is leaking into the bilge. Not sure why the float switch wasn't working, but when I opened the access port at the aft bilge, this is what I saw laying on the bottom. I've worked in that bilge before and installed a new transducer, not having seen this previously, so I'm a bit puzzled. Looks like it might be a bilge pump mounting flange or something like that.... can anyone identify it?

 

[Keitha]

I can't seem to get a sense of scale on that - It could be 6" diameter or 2". How big is the piece? My first reaction is same as yours; a macerate or bilge pump flange.
Does/did it have a head? it could be a backing flange on the toilet...

 

[Greyduk]

The color makes me think it looks like the flange from a battery selector switch.

 

[Parthery]

I think Greyduk nailed it. Looks like the outside flange from the battery switch....or a previous battery switch.

 

[Uncle Binky]

I can't seem to get a sense of scale on that - It could be 6" diameter or 2". How big is the piece? My first reaction is same as yours; a macerate or bilge pump flange.
Does/did it have a head? it could be a backing flange on the toilet...

It would be a 5 1/2" OD were it not broken.

 

[Uncle Binky]

The color makes me think it looks like the flange from a battery selector switch.

You nailed it - broken flange from battery selector switch. Can't imagine how it got there - those switches are separated from the bilge by a bulkhead. Gotta be from the PO.