The people of Zwen gained the power to turn into stone as a way of hibernation on a planet whose night takes about six months long. Throughout on most of his missions, Stone Boy could only transform into an inanimate, stone statue and was often used in numerous ways such as being dropped on a villain from above by his teammates, or at best as a distraction while the other "Subs" carried out some mission was found to be humorous.
In one instance he is used tactically, as something for his allies to throw enemies at. During some time he underwent hypnotherapy and gained the ability to stay conscious during his transformation and, eventually, even to move in his stone state which was a major achievement for himself. On occasion he has been shown transforming only part of his body to stone, but that didn't seem to stick.
He was the first member of the Legion of Substitute Heroes to be offered Legion membership, but turned it down. He and several of the other Subs played key roles in Legions 5YL storyline. He also appeared in the "Subs" episode of the Legion cartoon.