Is this part really needed?
 

In the process of draining coolant out of the engine block, I noticed this piece was partially in place/dislodged on the front of the torque converter case.

It looks like it had partially been knocked into the t.c. and was chewed up a little but was still hanging in there.

Parts shops identify it as "oil pan cover" but I think that's incorrect.

Is this piece essential and replaced or unnecessary. It doesn't seem to be a very sturdy piece. Will replacing it reduce noise from that area?

This was on a 94 c280. I checked my 96 c280 and it was completely gone. Again, it doesn't cost very much, less than $2, but would it just get knocked out and cause more problems, i.e., being completely knocked into the t.c. case. Apparently, it looks susceptible to that. It looks like it would get chewed up easily, though, as it is cheap, pretty brittle plastic not even rubber.

It's a cover to protect the opening in the bell housing. Without it, more road grime and crap gets in there, some finding it's way to the seal between the TC and front pump. It's only $2.

I'm curious now. Why do you think they didn't use a sturdier piece? Is this an area that needs to be accessed often? Can't be permanently closed? I know to drain T/F fluid from the TC the access is on the other side. Sorry for my ignorance, but what pump are you referring to? What does dirt & grime potentially screw up here? Thanks.