Hallucigenia Worm was a Bizarre, Spiked, Sea Creature of Nightmares (VIDEO)

First Posted: Jun 25, 2015 06:47 AM EDT

Scientists have uncovered a strange, otherworldly creature that once lived half a billion years ago. This nightmarish, work-like animal had legs, spikes and a head difficult to distinguish from its tail.

The animal is known as Hallucigenia due to its strange appearance. In this latest study, the scientists found that the creature had a throat lined with needle-like teeth, which may help researchers connect the dots between modern velvet worms and arthropods.

Arthropods, velvet worms and water bears all belong to the massive group of animals that molt, known as ecdysozoans. Although Hallucigenia is not the common ancestor of all ecdysozoans, it is a precursor to velvet worms. In fact, this species shows that velvet worms originally had the same configuration, but it was eventually lost through evolution.

"The early evolutionary history of this huge group is pretty much uncharted," said Martin Smith, the lead author of the new study, in a news release. "While we know that the animals in this group are united by the fact that they moult, we haven't been able to find many physical characteristics that unite them."

In fact, it turns out that the ancestors of molting animals were much more anatomically advanced than the scientists could have imagined. Hallucigenia were ring-like, plate-bearing worms with an armored throat and a mouth surrounded by spines.

"Prior to our study there was still uncertainty as to which end of the animal represented the head, and which the tail," said Smith. "A large balloon-like orb at one end of the specimen was originally thought to be the head, but we can now demonstrate that this actually wasn't part of the body at all, but a dark stain representing decay fluids or gut contents that oozed out as the animal was flattened during burial."

The findings reveal a bit more about the animal, and show quite a few new anatomical features. It had an elongated head with a pair of simple eyes and a mouth with a ring of teeth.

The findings are published in the journal Nature.

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