Characteristics:
This cactus presents stem with a wavy-like growth that tend to fold over itself, giving its peculiar "brain" shape (kinda obvious but that's why it's popularly known as Brain cactus". This particular shape makes this specie quite used for decorative purposes. Generally it does not have central spikes but rather a quite large and abundant number of radial spikes that can be yellow or kinda-red toned.

Cares:
Tolerates very well direct sunlight and hot temperatures but not so well cold weather. It's recommended that it is planted on well-drained soil in order to avoid water accumulation that might rot the roots. Another fact that must be taken into consideration while watering it is to make sure that there is not water left between the folds of the stem, as it is an ideal place for insect proliferation (which may in turn lead to some kind of moisture decay that could kill the plant). In general, watering can be done once a week during the hot seasons and once a month during the cold ones (always making sure that the soil is dry before watering).

Flowers:
They usually appear round summer and spring, being three color possibilities: white, pink or yellow. I own the specimen from the picture and I've had it for something over a year or so but it hasn't bloomed yet so I can't tell specifically what color its flowers are. Nor it has given me any fruits whatsoever.