Petra was born in America while her family immigrated from Denmark. Soon after her thirteenth birthday, a rock slide killed her family except her. She was baffled as to why she wasn't killed. She was placed in a foster home, where her foster father acted strangely towards her. One day while they were vacationing at NYC's Central Park, he attempted to molest her, only to find that the ground was suddenly swallowing him up. Petra was terrified as the man called her a 'freak', 'one of those mutants.'

Not wanting to be placed in another home, Petra became a runaway. She began manipulating nearby caves to provide her with a safe and secure hiding place. At 16, she discovered she could turn coal into diamonds. She found a pawnbroker to sell to. One day, the pawnbroker made an excuse to call the shop owner, causing Petra to flee. She woke up in a holding cell, where she was told she had a visitor. This visitor had dropped all charges and convinced the authorities to release her in her care. This visitor was Moira MacTaggert.

She eventually joined the newly formed X-Men who were sent to Krakoa to resuce the missing members of the original X-Men team. She was killed during the mission, but her actions saved Darwin and Vulcan.