What in the hell is this?
http://guntramwolf.de/instruments/modern/basson/index_basson_mod_e.htm
diagram two on that link-that thing that sticks out next to the low d,c,b and bflat, what in Samael's unholy name is that?

If you're talking about that square key in the middle, it's like an extra low C key (put down C and D key), as far as I know. It's to get from low Bb to C easier.