The sound for this unusual short instrumental was created by Tool lead singer Maynard James Keenan's Cat. The sound is actually Maynard's cat being squeezed and the resulting sound slowed down to create the low pitched noise. (thanks, Craig - Blairgowrie, Scotland)
The Mantra is the subtle hum of the soul and spirit it brings all communication of the body to one. (thanks, Dan - Stourbridge, England)
"Mantra" is about 1:10 long, and maybe 25 seconds are featured in the "Schism" video.