Splitting/Dividing an Edge

I am working on a personal project, and part of it is making a rubber duck. All was well until I got to the beak, which I made a cube with a loop cut for the basic mesh. Is there a way to split or cut it in half so it can “open”? Kind of like the opposite of merging two vertices. I remember doing this for another project, but all I can remember is making the edge I want to split a “sharp”. Does anyone know how to do this?

Rip ? (shortcut V)

Thank you! I can’t believe I forgot that… :stuck_out_tongue: