Help!!!

[suki_blue]

I'm writing fic and I need to know the name of a contraption. It's a sticky-up thing that you pull sideways to set it off and then it wobbles side to side counting beats. I've seen it used in films when someone is playing an instrument or to hypnotize someone.

I just can't think what it's called and I can't think how to accurately Google it.

Please to be helping me?

EDIT: It's a metronome. Thank you pinkfriction and sweet_exile