Mystery "Menu Extra"
opensnoop
You can also use opensnoop to get more info on the icon. opensnoop is a Terminal app, it is pre-installed on your mac. When run with no options, opensnoop just prints all the files that are accesed on your computer in real-time

open Terminal.
type sudo opensnoop, your console will fillup fast.
click the icon.
look at the console to see which PID or which program get triggerd when clicking on the icon.