Despite having no blood supply, a heart, or brain, jellyfish are incredibly slimy. Jellyfish are among Earth’s most common ocean creatures, and various species are found in all the planet’s oceans. They’re among Earth’s oldest creatures that have been around for about 500 million years (250 million years older than the first dinosaurs). Scientists from Toronto’s Royal Ontario Museum found the most senior jellyfish swimming in fossil records. Burgessomedusa Phasmiformis is detailed in a study published on August 1. in Proceedings of the Royal Society B.

Jellyfish are part of a clade of creatures known as medusozoans, including box jellies; hydroids stalked jellyfish, and the real jellyfish found in today’s oceans. Medusozoans comprise the category of Cnidaria, including sea anemones and corals. Discoveries of Burgessomedusa are proof that jellyfish of a large size with a bell or saucer-shaped bodies were already evolving over 500 million years ago.

Jellyfish comprise around 95 % water, making them difficult to preserve in fossils. However, the Burgessomedusa fossils have been exceptionally well preserved within the Burgess Shale in the Canadian Rockies. It is home to the Royal Ontario Museum. It currently houses more than 200 pieces of fossils used to discover more about the anatomy and tentacles of early jellyfish, and some specimens are more than seven inches long. As with modern jellyfish, Burgessomedusa was also capable of swimming freely. Their tentacles could have helped in catching pretty big prey.

“Although jellyfish as well as their cousins are believed to be one of the first animals to evolve and evolved, they’ve been extremely difficult to identify on the Cambrian fossil record. This finding proves that they were swimming around in the early Cambrian,” study co-author and University of Toronto Ph.D. candidate Joe Moysiuk stated in an announcement.

The study is based on fossils discovered in the Burgess Shale during the late 1980s and the 1990s. The fossils show that a Cambrian food chain was more complicated than what paleontologists had previously thought and that the massive arthropods that were swimming at the time, such as Anomalocariswere, were indeed not the only predators.

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One of the most gnarly parts of the intricate life cycle of Cnidarians is that they could have multiple body shapes. A vase-shaped non-free swimming body is known as a polyp, and medusozoans possess the form of a saucer or bell, known as the medusa or jellyfish. These bodies can be free-swimming or non-free. The fossilized polyps have been discovered in rocks approximately 560 million years old. However, the source of the medusa, which is more free-swimming or jellyfish, needs to be better comprehended. Their evolutionary history depends on the microscopic fossilized larval stage and molecular studies on living species.

“Finding these delicate creatures preserved in the rock layers over the mountains is an amazing discovery. Burgessomedusa is a further addition to the complex nature of Cambrian food webs. Like Anomalocaris which was found within the same ecosystem they were effective predators of water,” study co-author and Royal Ontario Museum’s curator of invertebrate paleontology Jean-Bernard Caron said in an announcement. “This adds yet another remarkable lineage of animals that the Burgess Shale has preserved chronicling the evolution of life on Earth.”