In your last picture it looks like you circled part of that check valve. Is that true? Take a look at this:
Audi B5 A4 FWD 1.8T > Engine > Intake > Check Valves > ES#258791 Check Valve - 07C133529A

 

Yes it is a check valve I guess( i say I guess because everyone else is saying so.) That part you listed is the same thing that I posted from ebay but almost three times more expensive so I am going to buy the one off ebay. Thanks guys