Unsure of washer location

Working on the water pump of a 1998 Mercury Sable (OHV)

In taking apart my water pump, I was careful to make sure I noted where all the fasteners and other components came from.

However, I've come across what appears to be a washer with three small holes around the large central hole. I do not remember removing this washer, but here it is.

The most frustrating part is that it seems to fit in many places, but at the same time it doesn't seem to make sense in any of those places.

I have a hunch though: I think it goes behind the drive belt tensioner pulley. It fits there, and that's the only place I figure I could have missed it.

I'm pretty sure the same tensioner I have is used on like 20 years of Tauruses, so if anyone could try to look and see if there is such a "washer" (I'm not even sure that's what it is ... it just kind of looks like a washer) on the back of the tensioner pulley, that'd be amazing.

EDIT: Nevermind, it makes absolutely no sense back there.

Or anywhere else in that general area....

In this image, the ring with three small holes around one large hole is pretty much exactly what I'm talking about. However, I definitely haven't done anything to the crankshaft.

Any ideas where else it might go?

http://www.fordtechservice.dealerconnection.com/pubs/auxf/~WS-V-B/1599/A15297B.gif

The more I think about it, the more I believe it must just be some leftover from something someone did before I owned the car. It doesn't seem to be needed anywhere, nor do I have any leftover bolts to put into the 3 extra holes.

Hopefully it's a part that was replaced ... and not one that was forgotten.