It is a globose cactus, spherical or a little flat, with a diameter up to 8 cm, dark green in colour, or sometimes brown. It has 8 to 10 ribs with tubercle-shaped areoles, covered in groups of 6 to 8 pale grey, curved spines, giving to the species its common name of spider-cactus. Like many cacti, it does not divide but may form offsets after some years. The funnel-shaped flowers reach a diameter of 6 cm, growing near the apex of the plant and are red, pink or orange.