missing transmission plug?

[peter]

While poking around yesterday I noticed gears were visible through the transmission housing and thought to myself... was it always like that?? Can't say I've noticed it open or closed before. What are everyone else's 2.0 TDI manual transmission housing like?

I did notice residue around the edge of the hole, as though a plug used to be there but now isn't.
Has it dislodged or is it exposed just like this? ...doesn't seem right that an upward opening to the transmission remain exposed.

TIA

[Creniac]

Looks like the flywheel to me..... not a huge problem because it's dry in there (no oil) but yes I would be sourcing a plug pretty quickly to stop any unwanted materials like water getting in there.