High Quality Content by WIKIPEDIA articles! Xenusiids (class Xenusia) are a group of lobopods resembling Xenusion. They have relatively large, annulated, cylindrical body. Their lobopod legs have tubercles at their bases. Some have large frontal appendages, although these may represent taphonomic artefacts. Their mouth is terminal or subterminal, and they are marine. They probably represent a grade (paraphyletic group) rather than a clade (monophyletic group).