The nautilus is considered to be a living fossil. It's remained largely unchanged for the past 500 million years, since the Triassic period. The nautilus usually inhabits ocean depths of about 300m, rising to around 100m at night only for feeding, mating or laying eggs. The average lifespan of a nautilus is around 20 years.
SUPERBLY ELEGANT FOSSIL SEA LILY Seirocrinus subangularis Lower Jurassic Posidonienschiefer Formation, Holzmaden, Baden-Württemburg, Germany The Crinoid, known also as the Sea Lily or Feather Star, is one of the world's so-called "living fossils", with species still to be found in today's oceans from Indonesia to the Caribbean.
Living Fossil The earliest horseshoe crabs were found 450 million years ago as fossils in strata. Many think of them as crabs and crustaceans when in fact they are more related to spiders and scorpions. Under their enormous shell, their bodies also look more like those of spiders.
endangeredanimalblog: The COELACANTH is referred to as a living fossil because it is the only remaining species of a group of fish species that died out millions of years ago. It is found in the deep coastal waters of eastern Africa, where rocky shores are battered by strong oceanic currents. A large fish, growing to a length of about 6 feet, and it moves along the rocky slopes with the help of fleshy pectoral fins. Populations are thought to be critically low.