When Dag Wentim (Stone Boy) found out about the Legion of Super-Heroes, he thought that he stood a chance of joining them since he is almost indestructible in his stone state. Unfortunately, Dag's ability was considered too limiting because he was stationary in his stone form and it was difficult to communicate with him in that state. However, Stone Boy soon met up with a group of other Legion rejects and they formed the Legion of Substitute Heroes.