Fossil jellyfish from the Cambrian Mt. Simon Sandstone in mid-Wisconsin. These are imprints, up to a meter across, of the bell and its anatomy preserved as the jellyfish were stranded on a shallow tidal sand flat some 525 million years ago. These and other soft-bodied fossils are being studied in Jere Lipps's lab in the Department of Integrative Biology. This work on fossils is combined with molecular sequencing of basal invertebrates to get a clearer understanding of the early evolution of animals.