An article published in the journal “BMC Evolutionary Biology” describes a research on Habelia optata, an arthropod that lived in the mid-Cambrian period, about 505 million years ago. It’s one of the many organisms that lived at that time whose fossils caused perplexities in paleontologists with difficulty in their classification. Now Cédric Aria of the University of Toronto and Bernard Caron of the Royal Ontario Museum believe it was related to the ancestors of the current species of the chelicerate subphylum.