Morphology, Paleobiology and Systematics of the Mobergellids, a Group of Cambrian Problematic Fossils

Possible variants of systematic position of Cambrian problematic fossils of the family Mobergellidae are discussed. An affinity between mobergellids and Sipuncula, a phylum of marine benthic worm-like lophotrochozoans possibly related to annelids, is proposed for the first time. The mobergellid discoidal sclerites are interpreted as caudal shields of sipunculans