You've heard of the woolly mammoth. But have you heard of woolly mice? These critters were genetically modified by the Dallas-based biotech company Colossal Biosciences to have the same "woolly" and fat appearance as the ancient mammoths. The mice are a key step in the longer journey to de-extinct the woolly mammoth. NPR's Rob Stein takes us to the lab where it all happened.Interested in more biotech stories? Let us know by dropping a line to shortwave@npr.org.Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy