A small shark swimming around a Louisiana aquarium holds a mystery in its DNA. Yoko the swell shark hatched from an egg that was discovered in a puzzling place — an all-female tank, the Shreveport Aquarium announced. “It really proves that life ... uh ... finds a way,” curator Greg Barrick said in a Jan. 24 news release.

The Shreveport Aquarium in Louisiana is investigating the mysterious birth of a baby swell shark, despite no male sharks being present in the tank for three years.

Last February, a similar situation occurred in Hendersonville, North Carolina, when a stingray at the Aquarium & Shark Lab was found to be pregnant despite living in a tank without a male of her species. The aquarium determined the stingray, Charlotte, had developed a rare reproductive disease that negatively impacted her reproductive system.