MCXMenuExtraTool, what is it and why is it in my Login Items?

Hello, I have just noticed that I have an item called MCXMenuExtraTool in my Login Items of my PHD accounts. I spent an hour or so last night trying to get rid of it (delete local account & prefs, and re-sync), but to no avail. This morning I created a new test account, and unless I'm mistaken, it only appears after enabling PHD.

I'm guessing it's supposed to be there, but why?

Thanks