BBCnews is carrying this story on the discovery of a strange fossil critter that is proving rather resistant to classification into existing phyla. Called Vetustodermis planus, this 2-4 inch long beastie lived 525 million years ago, in the heart of the Cambrian period.
While currently classified as a mollusc, the creature really doesn't have the full set of tell-tales that would allow it to easily fit there. Readers of Jay Gould's Wonderful Life will be nodding their head, since one of WL's key premises was that the Cambrian period saw the rise and fall of several phyla that no longer exist. However, further research has cast severe doubt on this hypothesis, and most of the examples Gould used were later fit into existing phyla. Other biologists, of course, disagree.
Which means we've strayed into the esoterica of scientific politics, where giants stomp and roar at each other over things that make the rest of us go, "wha?" So let's just all sit back and wonder at the remains of a critter who lived at a time when complex life forms were the new "in" thing, and the only things living lapped at the shores of silent, desolate continents of sand and stone.