Marocella: Antarctic specimens of an enigmatic Cambrian animal

Remarkably well-preserved specimens ofMarocellaGeyer, 1986, from the Lower Cambrian Shackleton Limestone of Antarctica show that although affinity with chondrophorine cnidarians is improbable, its rigid caplike shell also is unlike that of any known mollusk. Association with sclerite-bearing taxa cannot be ruled out, but at present the phylogenetic affiliation of the genus remains equivocal.