Anaerobic Multi-Cellular Life Found

Physorg is running an article describing the discovery of the first modern multi-cellular life that does not metabolise oxygen. Obvious implications for finding life elsewhere than Earth.
http://www.physorg.com/news189836027.html

Paper here.

I guess it evolved from oxygen-using ancestors though. Though definitely is nice to see that you can have anaerobic metazoans.

Cool, however I can't help but ask if the body type and system would be entirely different, as it's not metabolizing oxygen, resulting in an entirely different metabolisim (no pun intended). By the way, what is is metabolising if it's not oxygen?