Pot: 10 cm.
This cactus exemplar shows two characteristics that make it very sought after by collectors: on the one hand thanks to its crested shape it has a very particular fan crest and , on the other hand, it presents anomalies in the shape or absence of spines typical of the monstrous form. These particularities will never be found identical in two different plants, for this reason each specimen is unique in its kind. In its normal form M. knippeliana is a solitary cactus that sometimes during growth becomes dichotomous. It has a globose stem, slightly cylindrical, equipped with very evident pointed tubercles, at the apex of which emerge, from woolly areoles, small white and well straight spines. In the grooves between the tubercles, as well as at the apex of the plant, is present the typical whitish fluff that distinguishes many Mammillaria and gives it a seemingly soft appearance, in contrast to the hard and shaggy one that gives it the thorns, for a very scenic overall appearance.