Money quote from the article Worm turns out to be one of man’s closest relatives:
“Up until now Xenoturbella had been thought to be related to the bivalve molluscs – which include mussels and oysters,” said Dr Telford. “We found this hard to believe as it looks nothing like a bivalve mollusc.”

I find this amusing in light of the fact that they discovered that the worm was closely related to man. I would have thought the worm looked more like an oyster than, say, Dr. Telford.