What is this and where does it go?



This was in my baggie of bolts for the camshaft holders (tore everything apart to replace the headgasket). It is 10mm long and diameter looks to be 7mm. It's slightly smaller that camshaft holder dowels, and I've got all of those in place. There's only one of these but I can't seem to find a logical place for it to go. The shiny machined look tells me it's very necessary, so I don't wanna go to far without it.