Ancient shrimp had a cardiovascular system 520 millions years ago, earlier than any other living creature ever did.

According to Reuters, a team of researchers discovered the oldest known cardiovascular system thanks to a pristine fossil of the shrimp's heart and blood vessels. The team named the arthropod Fuxianhuia protensa and determined the invertebrate would be a relative of crabs, lobsters and shrimp.

The research team published their findings in the journal Nature Communications.

"It is an extremely rare and unusual case that such a delicate organ system can be preserved in one of the oldest fossils and in exquisite detail," study researcher Xiaoya Ma, a paleontologist at the Natural History Museum in London, told Reuters. "However, under very exceptionally circumstances, soft tissue and anatomical organ systems can also be preserved in fossils."

Found in the Yunnan Province southwestern China, the fossil dates back to a period when the "Cambrian Explosion" marked the expansion of a vast majority of the species on Earth.

"Fuxianhuia is relatively abundant, but only extremely few specimens provide evidence of even a small part of an organ system, not even to speak of an entire organ system," Nicholas Strausfeld, director at the University of Arizona Center for Insect Science, said in a press release. "The animal looks simple, but its internal organization is quite elaborate. For example, the brain received many arteries, a pattern that appears very much like a modern crustacean."

In F. protensa's fossil, the researchers found a tubular heart in the middle of the creature's body and vessels connecting it to its eyes, antennae, brain and legs. Not all animals have a cardiovascular system, such as the jellyfish and earthworm. The researchers were excited to find how ancient creatures bore several similarities to animals alive today.

"It appears to be the ground pattern from which others have evolved," Strausfeld said. "Different groups of crustaceans have vascular systems that have evolved into a variety of arrangements but they all refer back to what we see in Fuxianhuia.

"Over the course of evolution, certain segments of the animals' body became specialized for certain things, while others became less important and, correspondingly, certain parts of the vascular system became less elaborate."

Now the researchers plan to analyze the specimen closer and possibly even recreate how F. protensa would have behaved.

"With that, we can now start speculating about behavior," Strausfeld said. "Because of well-supplied blood vessels to its brain, we can assume this was a very active animal capable of making many different behavioral choices.

"This is another remarkable example of the preservation of an organ system that nobody would have thought could become fossilized."

(The author of this article fixed an incorrect statement made about the Cambrian Explosion).