Tephrocactus. See more pictures of cacti.
When the tephrocactus are very young they have tiny leaves that soon disappear. They have many glochids (barbed hairs or bristles) that break off in the hand at the slightest touch and are found sometimes even inside the fruit. The spines are usually long and add interest to the plant.
Tephrocactus flexispinus is made up of globular sections that are covered with flexible spines. Tephrocactus paediphylla has very long spines that are somewhat flattened and twisted. The spines grow out of cylindrical segments that grow on top of each other a bit like sausages.
Give them bright light, heavy soil with excellent drainage (broken up bricks do very well) and drench and let dry. They are slow growers and do not need much water even in the summer time. In fact, with these, less is usually better than more. They will tolerate dry air and winter temperatures just above freezing.
Caring for your cactus: