full moon gasket seal ??

[2GturboTALON]

I noticed there was a puddle under my car when i pulled out of my parking spot. I then popped the hood and looked around and noticed im missing the piece that that covers the cam. It is not the half moon one though. What is this piece called thats missing. I babied it home about 2 miles away but didn't notice any problems. Also does anyone know if these are stock cams? Ive never torn the engine down and previous owner tols me it was slightly built. the serial on the cam shows (411300516)
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[turbosax2]

http://www.dsmtuners.com/forums/newbie-forum/308725-resolved-cam-angle-sensor-seal-plug.html

 

[2GturboTALON]

Im assuming by how easy it fell off , i can just clean everything up and dry and place the plug on there with a little gasket sealer. Is that right?