On Mar. 4, 2025, scientists at Colossal Biosciences announced that its scientists have simultaneously edited seven genes in mice embryos to create mice with long, thick, woolly hair. They nicknamed the extra-furry rodents as the “Colossal woolly mouse.”

It’s been 4,000 years since the eight-ton, 12-foot, elephant-like beast walked the Earth, but part of its DNA now operates inside several litters of four-inch, half-ounce mice created by scientists at the Dallas-based company.

The mice don’t have their characteristic short, gray-brown coat, but rather the long, wavy, woolly hair of the mammoth and the extinct beast’s accelerated fat metabolism, which helped it survive Earth’s last ice age. Both traits are the result of sophisticated gene editing that Colossal’s scientists hope will result in the reappearance of the mammoth itself as early as 2028.