Stubborn bathtub drain.....

[Mike OConnor]

I am hoping that someone can give me some help as to how I can remove this drain. A standard drain removal tool will not work as there are no crossbars, just the two slots you can see on either side of the drain. The guy at the plumbing store told me he had never seen a drain like this one and I am hoping that someone on the internet has not only seen one, but has successfully removed one! Thanks for any advice you can give in advance.