The results were unexpected because the comb jelly is much more complicated than the sponge, having tissues and a nervous system. It is frequently assumed that the more complicated animals would be found further along the evolutionary chain. This finding suggests that the earliest animals were then more complicated than previously assumed. So either the comb jelly evolved its complexity distinctly from other animals after branching off or the sponge became a more simple animal after it branched away. As Casey Dunn, one of the authors on the study hastens to point out, "evolution is not necessarily just a march towards increased complexity. This scenario would provide a particularly dramatic example of that principle."