The tadpole shrimp is one of several "living fossils" -- creatures that are still living today, but have remained unchanged for millions of years.
"The Tadpole Shrimp (Triops cancriformis) is a living fossil, thought to be the oldest living creature on the planet. Resembling a small Horsehoe Crab, it has been recorded from at least 220 million years ago in the Triassic period, even before dinosaurs roamed the earth, and may be as much as 300 million years old."
