What is this pen-like mouse-like device that connects to a probably-computer via a connector I dunno what it is?

There’s a nub on the end of the device that makes it look pen-like, and the metal loop-ish bumps click like mice buttons.

Is it just an obscure mouse form-factor? If so, then what kind of port am I looking for to connect it to a PC?

Or is it not a PC peripheral at all?