FORGET THE elephant shrew—meet the mammoth mouse. On March 4th Colossal Biosciences, a company trying to revive long-gone species, announced that they had genetically engineered a Mus musculus to have qualities of the extinct Mammuthus primigenius. Instead of earth-shaking stature or enormous tusks, the creature possessed an abundance of dense, golden fur. It was, in other words, adorable. “That was the main unintended consequence,” says Ben Lamm, Colossal’s boss and co-founder.