This is a relatively rare member of the marine (Essex) portion of the Mazon Creek deposit. Hesslerella shermani looks to the casual observer to be some type of shrimp. It is actually a marine isopod related to modern day pill bugs. One of the main features that differentiate it from a shrimp is that it lacks a carapace. Other distinguishing characteristics are a rounded head with large eyes. The legs are also similar in length. Hesslerella is one of the smallest crustaceans