Regeneration is a remarkable phenomenon in which an animal can regrow parts of its body that are lost or damaged by injury. Humans, for example, can repair some organs, but some animals can rebuild their entire bodies from small pieces of tissue. How do these animals accomplish this feat? And why is it that humans cannot regenerate as well as these animals can? Studies of how regeneration works at the molecular and cellular level are beginning to answer the first question. To answer the second question, we have to understand how regeneration has evolved. Mansi Srivastava highlights major insights about regeneration based on her team’s research on the three-banded panther worm, a marine invertebrate species that enables us to study how regeneration works and how the process has evolved.