Help identify engine part on 1998 Audi Cabriolet

[edangs]

Help identify engine part on 1998 Audi Cabriolet?

please check link to see image of the part. it has broken/crumbled and need replacement. when car is running, air is coming out although no adverse effect. car has 120k miles.

http://www.geocities.com/edangs/audi.html

thanks
ed

[YODASFRO]

Vacuum check valve.