An unusually well preserved phosphatic fauna has been found in boulders of Lower Cambrian conglomerate from Venenas, on the Skaggenis Peninsula in the Baltic Sea. The fauna is dominated by the problematic fossil Mobergella holsti (Moberg 1892). The present material shows that this form is composed of three separate taxionomical units, and two new species - M. radiolata n. sp. and M. turgida n. sp. - are introduced besides M. holsti. The new evidence seems to discard entirely the theory that Mobergella has been a free-living organism of monoplacophoran type. Instead, the interpretation of the shell as the operculum of a tube-dwelling organism seems to be the most plausible one. The tube itself, however, has not been recovered.