Recently on the blog Neatorama they highlighted a very strange creature, a parasite of the lobster that is pretty unrelated to other animals - Symbion pandora. Its got a rather complicated reproductive cycle, as described in the links below.
The articles mention that it was so unusual that a new phylum was proposed, the Cycliophora. I was curious about this so I looked up what sequences are available for Symbion pandora. There are some ESTs that are in the trace read archive, un-annotated as far as I can tell, and about 100 nucleotide records. Most of those are for RNA subunits, or cytochrome oxidase subunits, but there is one histone record. I've been reading about histones quite a bit recently so I BLASTed that record. It seems very suspicious to me that all the top hits were to lobsters (see alignment below, the top hit. Nephrops norvegicus is the Norway lobster). I strongly suspect that this was contaminated, and is not a correct Symbion pandora sequence.
The Neatorama link
More info is available from the New Scientist article that Neatorama links to.