Track 4 on Tool's 2001 album Lateralus. An instrumental interlude between the songs The Patient and Schism.
Note that I use the word "instrumental" in its loosest sense; there are no discernable instruments on this track. In fact, no one is quite sure yet what on earth this is. It has been theorized that it may be a series of heavily distorted whale calls, or simply some meditative chanting, as the title would suggest.
I have heard, though, that this track features "...a debut performance of a very special guest who also happens to be very close to one of the band members...". My personal best guess is that one of the band members will soon (or has recently) become a father, and this is a recording somehow related to that child. A recording of the fetus in the womb? The audio of an ultrasound? Maybe.
Of course, maybe this is just Tool's way of fucking with our heads again. If you have any theories you'd like to add, /msg me.
Uberfetus has informed me that Maynard has a son named Devo. We're getting there...
And the mystery may be solved: according to an interview with Maynard in the Japanese magazine Buzz, this track is the sound of him squeezing one of his siamese cats. It made such a weird noise that he recorded it, played it back super-slow, and made a track out of it.
Although Tool is renowned for outright lying to the press, this does seem to match up with what little information we had previously. I'd venture that it's probably solid.
Thanks to the Tool FAQ (http://toolshed.down.net/faq/)