Researchers have discovered that ancient shrimp had a cardiovascular system 520 million years ago, which is earlier than any other creature on earth. 

According to Reuters, scientists discovered that shrimp have the oldest known cardiovascular systems after studying a fossil of an ancient shrimp's heart and blood vessels. The team named the fossil Fuxianhuia protensa, and found that the arthropod is a relative of crabs, shrimp and lobsters. 

The research team, which is lead by study researcher Xiaoya Ma, a paleontologist at the Natural History Museum in London, published its 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," Ma told Reuters. "However, under very exceptionally circumstances, soft tissue and anatomical organ systems can also be preserved in fossils."

The fossil, which was found in the Yunnan Province in southwestern China, dates back to a period when the "Cambrian Explosion" killed a majority of Earth's species. 

"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," said Nicholas Strausfeld, director at the University of Arizona Center for Insect Science. "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."

The researchers found a tubular heart in the middle of the fossil's body, with vessels connecting it to its antennae, eyes, legs and brain. Not all animals have a cardiovascular system, so researchers were excited to find that ancient creatures bore similarities to animals that are 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," he added. 

The researchers now plan to analyze the specimen further, and possibly recreate how F. protensa would have behaved 520 million years ago. 

"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."