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Sandhill crane - Most of the birds on our planet have been around for about 1.8 million years. Sandhill cranes, however, have been here for 10 million years and counting.

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Lice - These parasitic insects have been tormenting humans for millennia. But they've been around for much longer: about 20 million years.

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Echidna - These cute spiky mammals have been around for an estimated 50 million years.

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Crocodile - You've probably noticed that crocs look a whole lot like dinosaurs. The difference is that these reptiles have managed to survive for approximately 55 million years.

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Cow shark - Unlike most sharks, the cow shark has six gills instead of five. They've been roaming our oceans for at least 60 million years.

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Giant freshwater stingray - These creatures can reach 5 m (16.5 ft) long and weigh up to 600 kg (1,320 lb). They've been around for about 60 million years.

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Bee - Bees have been buzzing around for 100 million years. Let's hope they continue sticking around!

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Platypus - This egg-laying mammal is native to Australia. It's believed that they have been on our planet for 110 million years.

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Green sea turtle - Like other animals on this list, these turtles have rubbed shoulders with dinosaurs. They've been on earth for approximately 110 million years.

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Goblin shark - These prehistoric, odd-looking creatures have been swimming deep in our waters for about 125 million years.

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Tuatara - An incredible 200 million years is how long these little fellows have been in New Zealand.

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Tortoise - They might be slow, but they've managed to win the race against extinction. Not many species have been around for 200 million years!

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Sturgeon - With barbels that look like whiskers, this big fish has swam in our planet's waters for about 200 million years.

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Tadpole shrimp - Contrary to what the name might suggest, these creatures are actually crustaceans. The species has survived for at least 220 million years.

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Horseshoe shrimp - One of the oldest species of shrimp on our planet, these crustaceans have been in our waters for 250 million years.

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Cockroach - Cockroaches have outlived dinosaurs, and continue to thrive after 250 million years.

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Lamprey -

With one of the most terrifying mouths in our waters, these snake-like creatures have been around for over 360 million years.

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Coelacanth - Previously believed to have gone extinct millions of years ago, this fish has actually survived for 400 million years.

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Elephant shark -

Despite the name, this is actually a ratfish and not a shark. They've been around for about 400 million years.

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Horseshoe crab - This arthropod is old⁠—very old. The species dates back 450 million years ago.

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Jellyfish - These gelatinous creatures don't have brains, bones, or hearts, but have managed to survive for 500 million years.

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Nautilus - This cephalopod does look like a fossil, and indeed it is a living one. About 500 million years is how long these creatures have been around for.

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Velvet worm - As the name suggests, these creatures possess velveteen skin. They've been crawling around our planet for at least 500 million years.

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Brachiopod - This is not your ordinary clam. These marine animals have been in our waters for 500 million years.

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Sea sponge - Yes, they do resemble a household sponge. It's estimated that these have been on our planet for at least 500 million years.

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Ctenophora - Also known as comb jellies, these are not your average jellyfish. They're among the most ancient creatures on earth: about 525 million years old, to be more precise.

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Cyanobacteria -

These truly remarkable creatures have been here for at least 3.5 billion years! It's almost unimaginable. 

See also: The largest animals in the world.

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