broken snap ring in oil

Do you have a picture of it? I think the Jake housings have snap rings.

 

Wrist pin snap rings are rather large.

 

I have stripped down a gearbox because on a routine service a bearing roller dropped out in to the oil pan.
An entire engine as well because of what looked like a piece of snap ring also dropped in to the oil drain pan during service.
On both occasions could not find anything wrong or missing after tear down.
Can only deduce they were left there some time before.
Very frustrating and costly and absolutely nothing can be learned from this because when parts drop out you have to find out from where.

On the other hand I have stripped a head off to do a head gasket that was leaking to find a deep gauge in the liner.
This was caused by the wrist pin sliding up and down the sleeve.
No snap ring in site .
Don't know if it wore away after coming loose or if it was never fitted.

I suggest taking the piece you found to an expert who rebuilds these motors regularly and see if it can be identified.
As mentioned a few good photos in the correct section here could help with your UFO (Unidentified flipping Object).

 

I used to be a service manager at a new car dealer. We have found things in oil pans that were "left overs".

We brought a fairly new vehicle in for a routine oil change, pulled the plug and the oil was barely coming out. We figured out it was a rod cap nut. Pulled the pan down and determined it was an extra from the factory.

Had a similar deal in a rear end of a pickup.

 

No pic coming thru.