Coryphantha Cornifera - Rhinoceros Cactus
A native of Mexico, this cacti's common name is Rhinocerous cactus, so called as it has 2 sets of spines, one large outward growing one from the aereoles and 7 - 11 smaller ones surrounding the base of the larger one.
Grows spherical to cylindrical to around 15cm in diameter when mature. Produces bright yellow 5 - 6 cm flowers in summer.
Keep dry in winter, with a minimum temperature of around 5°C, possibly down to freezing or lower if dry.