Corophium volutator (known locally as mud shrimp) are actually not shrimp but a member of a suborder of crustaceans known as amphipods. These fine fellows inhabit the upper layers of mud in the Bay of Fundy and play a vital role in this complex ecosystem.
Corophium keeps a very low profile: so low in fact that until a couple of decades ago Fundy 's mudflats (fully exposed at low tide) were considered lifeless wastelands of little ecological interest. But, as sandpipers have known for ages and scientists have recently learned, if you probe beneath the surface, the mud is home to unbelievably large numbers of these tiny amphipods.
For the etymologists in the familly: volutator comes from the Latin volutare, meaning "to wallow". Seems apt for these mud loving creatures!