Hmm, it sure looks like a dime to me.
Always remember to empty your pockets before leaning over the engine.
I'm not sure why you are comparing the dime to that other doohicky. I'm pretty sure a dime is dime sized.
Seriously, though, do you think epoxying screens over some of the oil passage inlets could have prevented that from happening? That really sucks. Did the cam gear get damaged, too?