Hybrids involving "obesa" can be some of the most interesting and unique.
Native to South Africa. Known as the Basketball plant. Great conversation piece. Avoid white sap from the interior of the plant. If you get in touch with it, wash thoroughly with soap and water. Protect from frost. Provide filtered light. This plant is hardy (36 degrees F). Water thoroughly when soil is dry.
Some of the information in this description has been found at desert-tropicals.com, llifle.com and cactus-art.biz