Lampreys are jawless fish that have existed for about 360 million years, surviving multiple mass extinctions.
These marine animals, resembling clams, have been around for over 500 million years.
Although now extinct, trilobites existed for about 270 million years
Sea sponges are among the oldest living animals, with a history spanning over 600 million years.
Often called a "living fossil," the coelacanth is a fish that dates back roughly 400 million years.
Jellyfish have been around for over 500 million years
Nautiluses are ancient marine mollusks that have remained relatively unchanged for about 500 million years.
1.Horseshoe Crab
These marine arthropods have existed for approximately 450 million years