This is one of the Mammillaria commonly called "Owl Eye Cactus", known for dichotomous branching (forking or dividing into two parts).

Cultivation: This plant is easy to cultivate but very slow growing. Cultivate it in a well drained and mineral substratum. Water regularly. It need full sun, so it keep a compact and flat shape. It does not tolerate intense cold, but tolerates some cold if kept dry. Frequent transplantations of the young plants protect the lower part of the stem.

 

Some of the information in this description has been found at desert-tropicals.com, llifle.com and cactus-art.biz

Bloom Season	Early summer early fall
Botanical Name	Mammillaria perbella
Dormancy	Winter
Family	Cactaceae
Flower Color	Purplish pink (darker mid stripe)
Genus	Mammillaria
Growth Habit	Globose
Growth Habit	Globose, cylindrical
Growth Rate	Slow
Hardiness Zone	9 11(USDA)
Mature Size	2.5 ft. wide
Native Area	Central Mexico
Plant Type	Cactus
Propagation	By seeds
Resistance	Drought tolerant
Resistance	Drought tolerant, pest resistance, deer resistance, mild frost tolerant
Soil PH	6.5
Soil PH	6.5, Acidic, Neutral
Soil Type	cactus potting soil
Special Features	Easy to grow
Sun Exposure	Full sun
Sun Exposure	Full sun, partial shade
Toxicity	Mild toxic to humans
Toxicity	Mild toxic to humans, pets(Keep away from children)
Watering Needs	Low