There is a really fascinating article on Science Daily today about Buddenbrockia, a small organism previously that has long been thought to be a nematode worm, but now known to be most closely related to anemones and jellyfish. It has no gut, mouth, brain, or nerve cord, and although it was long thought to be a type of nematode, it has a very different body plan (the main distinction: Buddenbrockia is symmetrical).
Researchers from the University of Oxford compared 50 genes with a variety of organisms to determine where this enigmatic species fits into the animal kingdom.
There are practical implications for this as well: apparently Buddenbrockia is closely related to a parasite that causes trouble for salmon farms (I don't have time to go into my issues with salmon farming the first place, though...). Current and future studies of it will hoepfully shed light on how to conquer the parasite, although I think that the taxonomic revelations are pretty cool all on their own.
(Photo credit: University of Oxford)