Intercrossing with this classification based on the social factor, on whether the totem is associated with the tribe, the individual, or the procreation of the individual, there is a second classification. The latter concerns itself with the nature of the objects that are regarded as totems. These objects are of various sorts. Here again, moreover, we must doubtless recognize a development in totemic conceptions. The original totem, and the one that is by far the most common, is the animal. Numerous peoples possess no totems except animals. In many communities, however, plant totems have been adopted, and in certain regions they have gradually become predominant. Of the plant totems, the most important are the nutritious plants. In addition to these two classes of totemic objects, there is, finally, another, though an exceedingly rare, sort of totem. The totem that is conceived as an animal ancestor may give way to other fanciful ancestral ideas or may intercross with them. Various forms of such phenomena are to be found, particularly in Australia. In this region, such ancestors, which, doubtless, are for the most part regarded as anthropomorphic, are sometimes called Mura-mura or also Alcheringa. They are apparently imaged as mighty human beings possessed of magic powers. They are believed to have introduced totemism and to have instructed the forbears of the Australians in magic ceremonies. Mura-mura is the name that occurs especially in Southern Australia; the term, Alcheringa, prevails in the north, where the age of these mythical ancestors is often directly referred to as the Alcheringa age. At times, apparently, it is believed that these ancestors merely singled out as totems certain already existing animals. In other cases, however, animals, as well as mankind, are held to have been created by the magic-working beings out of formless matter, doubtless earth. It is commonly believed that the creatures that were thus created were at first lifeless, but became animals and men when placed in the sun. These various ideas are for the most part so intertangled in Australian legend that no coherent history of creation is anywhere discoverable. The legends plainly embody merely a number of detached fanciful ideas.