Apparently identical marine animals called placozoans, once thought to all belong to a single species, are revealed by their genomes to in fact belong to different genera, according to a new study publishing on July 31 in the open access journal PLOS Biology by Michael Eitel and Gert Wörheide of Ludwig-Maximilians-Universität (LMU) in Munich, Germany, and colleagues. The genomic approach that they used is likely to be applicable to other groups of very small animals that lack physically distinct characteristics, including mites and nematodes.