A crayfish capable of cloning itself is taking over European countries — and the European Union has banned its transport, production, and release , reports The New York Times.

, The female-only population didn't exist 25 years ago but now numbers in the millions.

Scientists have discovered a mutation that allows the female crayfish to reproduce without a partner.

A crayfish that is capable of cloning itself is taking over Europe — and scientists are taking note.

The marbled crayfish has a mutation that allows it to clone itself, reports Carl Zimmer at The New York Times. Zimmer profiled scientists studying the all-female species known for its massive size, which "simply did not exist" 25 years ago.

The crayfish first became popular with aquarium owners because of their size and ability to lay copious amounts of eggs.

"As marmorkrebs became more popular, owners grew increasingly puzzled. The crayfish seemed to be laying eggs without mating," Zimmer writes.

Scientists soon discovered the genomic mutation, which has allowed the species to number in the millions. Zimmer does a great job of explaining how that works.

While the crayfish have never been seen in the wild in America, they are popular among hobbyists. They're banned in Missouri and Tennessee. The European Union also banned the species from being produced, distributed, or released in the wild.

Madagascar, where the crayfish are thriving, has become concerned about the size of the population. "There are a lot of clear advantages to being a clone," Zimmer writes. "Marbled crayfish produce nothing but fertile offspring, allowing their populations to explode."

It's unclear how long the population will be able to thrive.

People on Twitter were freaking out about the discovery.