Spring protruding from office chair?

I've had this chair for a few months and the other day I came around to get on the computer and noticed a decently sized lump in the chair.

Upon sitting on the chair it feels springy on parts (which left me to believe this is a spring bulging out) but rock hard on others. I don't want to mess with it too much without knowing what I'm even dealing with. Any advice on what it could be or what I should do to get it resolved?