Colossal Biosciences, known for its outlandish goal to resurrect the woolly mammoth by 2028, is claiming steady progress. It’s evidence: Genetically engineering mice to have mammoth-like fur.

To engineer the woolly mouse, the company’s scientists found mouse versions of mammoth genes and then used CRISPR to edit mice embryos, Dr. Beth Shapiro, chief science officer at Colossal, told TechCrunch. Then, those embryos were implanted into surrogate mouse moms.

The company says that the woolly mice’s fur is of a color, texture and thickness that resembles a mammoth’s traits.

Colossal Biosciences believes the woolly coat will enable its genetically-engineered mice to survive in cold climates. Still, the company must first obtain approval from the Institutional Animal Care and Use Committee (IACUC), which ensures ethical and humane animal research, before conducting such experiments.

Shapiro said the company needs to test the engineered mice’s cold tolerance to validate if those genes would improve the mammoth’s adaptation to cold environments.

Colossal’s approach to bringing back the mammoth involves mapping the entire genome of an extinct woolly mammoth and comparing it with its closest living relative, the Asian Elephant.

Investors have been impressed with the speed at which the company is creating technologies, Ben Lamm, Colossal Biosciences’ co-founder and CEO, told TechCrunch when the company announced a $200 million round at a $10.2 billion valuation in January.

In addition to working on a woolly mammoth, the company aims to bring back the Tasmanian tiger and the dodo bird.  

But that 2028 goal might not be realistic. According to David Gold, a professor of Paleobiology at UC Davis, producing multiple mutations in mice is hard, but it’s not nearly as difficult as creating a woolly mammoth.

“It is exciting to see the mice produce a mammoth-like coat. But there are hundreds of differences between the DNA of an elephant and a mammoth, so there is a long way to go,” Gold said. He added that while he believes that it will be possible to eventually re-create the woolly mammoth, there are a lot of technical hurdles ahead.

Still, Lamm calls Colossal’s creation of the woolly mouse a “watershed moment” for the company’s de-extinction mission.

“The animals were born healthy, and they had the exact phenotypes that we predicted,” Lamm said. “The only thing that was unintended was the adorability factor. They are just way cuter than we anticipated.”