Of the many species of Mammillaria, Cristata is the form known as the Brain Cactus, and it’s not hard to see why! It has multiple convoluted and sinuous growths with new growths overlapping old giving it’s unique structure. Their spines grow close together in various sizes, combined with the hair like spines this green plant gives off a grey-ish hue. Light and Water T need a good amount of light shade to full sun this help to keep the plants healthy, although slow growth. A sun facing desk or shelf, nestled in between other sun loving plants for partial shade will be a perfect spot while also being a talking point display. Water sparingly from March till October (weekly during summertime, if the weather is sunny enough) , with a little fertilizer added. Less or no water during cold winter months, or when night temperatures remain below 10° to prevent root loss. It is sensitive to overwatering.