Hi all,
I worked today on the bike and changed the air filter (I removed the tank and the seat). A rubber block dropped (unfortunately I missed it, but is something like this one. Size is about 3/4" x 1 1/2"). Do you know what is it for and where it is placed??:

I discovered also a rubber hose broken an disconnected (red colour on the picture).
I assume it has been like that for some time. What is it for? Should I replace it urgently?

Thanks a lot in advance!!