How do I get the tusk out of the very low room?

Hint 1 of 4:

There's no way to get it through the slit.

Hint 2 of 4:

The only way out is down into the sewer, although you seem to die when you go
there.

Hint 3 of 4:

Actually, if you go back up from the shaft and then down again, you'll be
able to get into the sewers.