Mammillaria "Fred" is a weird and beautiful monstrose form thought to be derived from Mammillaria bocasana. I could find no information about it's origins, so I don't know if it is a natural mutation that someone came across in the wild, or a mutation that showed up amongst some growers seedlings. It produces masses of tiny mostly spineless cactus heads that grow one on top of the other. In bright light the new growth is a bright red that fades to green as it grows very slowly. I doubt it produces any kind of flowers and can probably only be propagated by cuttings.
       I got this one from Arid Lands in May and so far seems to be doing OK, but showing little signs of growth. I have to experiment with location for it as I assume it requires bright light for good growth and color. I've seen a picture of this plant grown well in a pot, it's huge! Click HERE for a link to a page from Daves Garden that includes that picture. The picture below is a closeup of one of my plants heads, and then a late summer recap.

Closeup shot

later that summer