That's an ejector, it may be missing the latch spring or have a bad ejector spring, or someone converted it to a spring powered extractor, see the FAQs for a pic of all the parts and their relationship(minus the lift button which isn't used on rimmed cartridges/shotguns), there are links to permanent conversion to spring extractor which can only be restored with a new ejector claw or possibly an epoxy fix, but there's also a method for temporary conversion to extractor that can be undone, it's in the FAQs too. Shotgun ejector parts can be ordered from H&R, Brownells and Numrich.
Tim