Witness a snail scraping microbial films from the inside of an aquarium. Go back 505 million years, and this looks to have been the way an enigmatic early animal made its living (but without the aquarium). A faint shade on a piece of shale from British Columbia, Canada, has haunted palaeontology for 30 years. This is the fossil of Odonto-griphus, the half-a-billion-year-old 'toothed riddle' from the Cambrian Burgess Shale, which has never really found peace within the evolutionary scheme of animals,With a poorly preserved body, it was mainly known through peculiarly arranged tooth-like spines, hypothesized to be the stiff supports of a cluster of tentacles. On page 159 of this issue. Caron et al1 present new fossils of the 'toothed riddle' Odontogriphus at last comes, into clear view, with a firm body and prominent teeth. This view suggests that it is allied to primitive molluscs, and so provides fresh insight into the early evolution of animals.
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