A study by French researchers has found the coelacanth — a fish that has been around for 400 million years - can live for 100 years. These nocturnal fish grow very slowly and can ultimately reach the size of a human.

Female coelacanths reach sexual maturity in their late 50s, and a pregnancy takes about five years to reach full term. Known as a "living fossil," coelacanths were once thought to be extinct until 1938 when they were found swimming off the coast of South Africa. The slow-moving fish is so endangered the researchers who conducted the study could only examine already caught and dead specimens.