Hey, who’s that lady?

(Apologies to the Swiffer commercial.)  I’m wonder who that nun is.  She looks VERY familiar and I’d bet she’s been on the show in another role before.  Anybody know?

I thought it was funny, she’s standing there talking to Melanie and all of a sudden she has to go because there’s a problem in the ER.  How did she know that?  Does she have ESP or something.