 Other "species" classified as "Spirillum" such as ""Spirillum minus"", ""Spirillum pleomorphum"", and ""Spirillum pulli"" are of uncertain phylogeny and in any case, these are names that have never been validly or effectively published and thus have no standing in nomenclature.Members of the genus "Spirillum" are large, elongate, spiral shaped, rigid cells.Some have tufts of amphitrichous flagella at both poles.