Maybe it was the infamous swan dress that caught Sir David's attention. Maybe he's got a weird Icelandic pixie fetish. Or maybe he just likes Bjork's music.
Whatever the case, the two of them have teamed up to produce a documentary on the nature of music.
In fact, that's what it's called: Attenborough and Bjork: The Nature of Music. Channel 4 in the UK has agreed to pick it up for later this year.
So, er, what's it about? Here's a quote from The Hollywood Reporter:
At the heart of the film is Biophilia – Bjork's cutting edge music project and accompanying interactive musical experience – exploring where nature, music and technology meet.
Sounds very academic. But it will no doubt be very, very interesting.