By Aly Semigran
Updated November 15, 2011 at 05:50 PM EST

Sesame Street has handled a lot of tricky tasks over the past 42 years, from teaching tykes the alphabet to explaining television to Keith Staskiewicz, but nothing quite like this before. Today’s Sesame Street PopWatch is brought to you by the letter M, for the Missing original Gordon.

In an open letter on their website, the Sesame Workshop explains that they’ve been on the hunt for an actor who played Gordon in an un-aired test pilot that was shown to a focus group of children in the summer of 1969. While all of the other Gordons (played by Matt Robinson, Hal Miller, and Roscoe Orman) are accounted for, they can’t seem to find the mystery man who originated the role of the beloved science teacher. No one, not even Big Bird (Caroll Spinney) knows who is he is… and Big Bird knows everything.

“We don’t know who he is, and we’d like to figure it out. We’ve tried everything short of asking the Internet, and come up empty. So we’re asking you for help…Email us with anything – anything – you know which could help us figure it out. Drop us a note a and we’ll start investigating. It could be something seemingly small; something like “my great aunt once said that her third cousin was almost on Sesame Street” or “there was a person in my neighborhood who said he was on Sesame Street in the late 1960s.” And as we learn more, we’ll post it here,” they plead on their site. Watch the hypnotic clip here to see if you recognize him. (Best moment: When Bert boogies directly into the line of view of the camera.)

Aside from, presumably, wanting Mystery Gordon to teach them those sweet, sweet dance moves, the Sesame Street crew explains that they’ve been on the hunt for him since 2009 when they were compiling research for their 40th anniversary. Any idea, PopWatchers? Do you know who Mystery Gordon is? Or are you more intrigued to find out why they stopped having groovy beat poetry followed by manic dancing? Share in the comments section below.

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