That "claw" is usually how the seatbelt is connected to the seat. If you ever feel or look down where the seatbelt connects to the seat, between the cushions, (at any seat I've ever noticed) you'll feel or see a hook exactly like that. In this case, I'm not sure why there are two straps coming off of the rectangular clasp, presumably both having the same hook. I guess they needed to lengthen the seatbelt but didn't bother removing the old hook? Somewhat odd, but assuming that it was firmly attached (the one going off into the seat I mean) then there's nothing to worry about.