The "66 million year old fish" usually refers to the Coelacanth (pronounced SEE-la-kanth), a fascinating creature often called a "living fossil." For decades, scientists believed that the Coelacanth had gone extinct at the end of the Cretaceous period—the same time as the dinosaurs—roughly 66 million years ago. However, in a shocking turn for the scientific community, a living specimen was discovered in 1938 off the coast of South Africa. This deep-sea fish is unique because of its lobed fins, which are fleshy and move more like limbs than the fins of a modern fish; this makes them an important evolutionary link between sea-dwelling creatures and the first four-legged land animals (tetrapods). Coelacanths can grow to over six feet long and live for up to 100 years. They inhabit the deep, cold waters of the Indian Ocean and the waters near Indonesia. Their survival for millions of years with relatively little anatomical change is a testament to the stability of the deep-sea environments they inhabit. Finding a "prehistoric" fish still swimming in the modern ocean remains one of the greatest biological discoveries of the 20th century.