ML320 oil leak

[gtrpicker]

1998 ML320. standing in front of the vehicle on the right side of the front of the engine block (I think in the cylinder head), there is a plate held on by 2 bolts. One bolt has come out and there is oil coming out from behind that plate. Before I dissassemble that side of the motor, what is the plate for (what's it called in case I have to order parts), are there any o rings behind it? basically what should I expect when I take it off.
Thanks guys
Michael

ps. I can barely see the part in daylight so I had no luck trying to photgraph it.