Adam, the person who shot Samus, explains to her that she cannot destroy the Metroids because they were engineered to have their weakness to extremely cold temperatures removed, and speculates that the reason he was able to freeze the Baby Metroid was because it had not reached the next stage of its life cycle, the mature Larval stage, where the invulnerability to ice would have surfaced. The Baby Metroid is named in concept art of the game.[1]