Mary Roach dives into the strange, funny, and unsettling world of designing new body parts, from pig hearts to prosthetic feet, revealing just how messy replacing ourselves can be. Replaceable You Subscribe to SiriusXM Podcasts+ to listen to new episodes of 99% Invisible ad-free and a whole week early. Start a free trial now on Apple Podcasts or by visiting siriusxm.com/podcastsplus . Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.