New work shows that physical folding of the genome to control genes located far away may have been a critical turning point for life on Earth. For evolutionary biologists, what most distinguishes the marine creatures called cnidarians and ctenophores is not the peculiar spelling of their names, nor the fact that they tend to be beautiful, but that they are among the oldest known groups of complex animals. Cnidarians (the “c” is silent) include jellyfish, corals and sea anemones, and their colorf...