Mammillaria sheldonii

It's a small cylindrical cactus of a dark green color, with white and short radial spines with darker shades on the tips. From the areoles long red-blackish spines, robust and hooked, emerge. At the base of the plant there are often numerous small suckers, from which new offsets grow. It has large funnel-shaped pink diurnal flowers, which sometimes have faded petals at the edges.