And it is not the only group that owes its survival to its stable habitat. They evolved 3.5 billion years ago, when life was just beginning and the Earth was very hot. Today, they live in water at boiling point in places like Yellowstone Park, and the essential features of their habitat are still the same. While some living fossils owe their existence to avoiding external change, others may have survived in their primeval form by slowing down their response to change. The tuatara, for example, is extremely long lived.
Individuals probably live for a century or more.
Nautiluses, the sole survivors of a group of shelled molluscs related to the octopus that dominated marine life around 300 million years ago, are also long-lived and reproduce slowly compared with their living relatives. Slow reproduction means that natural selection is slowed and helps explain why some living fossils haven't changed over time. It is something in their life history that's put them in an evolutionary straitjacket. But there are living fossils that have very short lives and reproduce ext- remely quickly. Think of cockroaches and archaebacteria.