Hallucigenia, a bizarre worm that lived around 500 million years ago, was one of the strangest creatures to ever live. These strange creatures lived during the Cambrian Period of geological, a time when multicellular lifeforms first came into existence. A vast increase in biodiversity at this time produced some bizarre creatures, but Hallucigenia was truly unique. The species did not seem to belong to any known family or tree of animals, leaving biologists without a way of easily classifying the creature.

Cambridge University researchers now believe they have discovered the only living descendant of the unusual creatures, a type of animal still alive on the Earth today.

Velvet worms, which make their homes in the underbrush of rainforest in tropical areas, were found to be the only known relatives of the ancient bizarre species. Despite their name, they are not true worms, as they achieve mobility through the use of a set of short legs. Claws at the ends of these legs grow in layers in both velvet worms, as well as  Hallucigenia. The modern species has a texture much like fur, formed by numerous mucous glands.

Hallucigenia grew to just between one-fifth and one-and-a-quarter inches long. Their backs were covered in spines, connected to seven or eight pairs of legs. Most biologists believe the spines were a form of defense for the animals, although that theory has not yet been proven. Members of the species also possessed ill-defined heads and tails.

The tiny animals likely scavenged for whatever they could find, as they crawled around the ocean floor.

Hallucigenia fossils have been discovered in large numbers in Canada and China, as well as scattered finds from around the world. While this latest evidence suggests the ancient creatures are related to modern velvet worms, other paleobiologists believe the species was an ancestor of modern arthropods, including crustaceans and  arachnids.

"Only the forward tentacles could easily reach to the 'head', meaning that a mouth on the head would have to be fed by passing food along the line of tentacles. Morris suggested that a hollow tube within each of the tentacles might be a mouth. This raised questions such as how it would walk on the stiff legs, but it was accepted as the best available interpretation," Princeton researchers wrote on their Web site.

Famed naturalist Stephen Jay Gould once stated his belief that Hallucigenia was not related to any living animal. That idea has now been challenged by the new findings.

Simon Conway Morris, a paleontologist who did the first in-depth studies of the fossils, coined the name of the species in 1979, in tribute to the creature's bizarre form.

Study of Hallucigenia, and how they are related to velvet worms, was profiled in the journal Nature.