The ruby ball cactus is a bright red, ball-shaped cactus that grows on a green base. A mutation of a normal cactus, it totally lacks the green pigmentation that allows other plants to absorb solar energy. The only way it can survive is to be grafted on a green cactus that absorbs energy for it. It is generally short-lived.
There are also yellow, orange, and bicolor versions of the ruby ball cactus. This plant only produces its pink blossoms under optimum conditions.