From Hidalgo Mexico, Mammillaria nana ssp. duwei is a variable globular cacti up to 2 inches in diameter. Some cluster some don't. Some have central spines and mine doesn't. Flower color varies as well. I bought this one for it's spination. Without centrals it's a very pettable cactus and in closeup view the spines are interesting indeed. They almost look like short versions of M. plumosas feathery spines, though quite a bit stiffer. A lot of the specimens in the group had offsets so hopefully this one will give me some pups this summer.