Worms are already pretty creepy, with their legless, squiggly body forms. But somehow the idea of worms with legs — probing, scurrying legs — sounds even more slithering. Such was life on Earth around 500 million years ago.

A new species of lobopodian, an ancient worm-like creature that may have been a precursor for modern day velvet worms, tardigrades and arthropods, has been described from fossils found in the Burgess Shale Formation in the Canadian Rockies, reports Phys.org. And it's downright alien-looking.

Lobopodians were not just worms with legs, but the new fossils show they also had strong, recurved claws on their back limbs, possibly for anchoring themselves on hard surfaces so they could stand upright. Meanwhile, they possessed two long pairs of spiky limbs towards the front of the body that were probably used to filter or collect food from water and bring it closer to their mouths.

Standing in 'perpetual ovation'

Researchers have named the new creature Ovatiovermis cribratus.

"The various adaptations of this new animal to anchored particle feeding are reflected in its name," explained Cédric Aria, a doctoral candidate at the University of Toronto and co-author of the study, which will be published in the journal BMC Evolutionary Biology. "The species, cribratus, is the Latin for 'to sieve,' while the genus name, Ovatiovermis, refers to that posture it must have ordinarily adopted: a worm-like creature that stood in perpetual ovation."

The existence of lobopodians has long been acknowledged, but few fossils remain of these evolutionarily important creepy-crawlies, so this finding has the potential to reveal a lot of new information. Only two known specimens of this particular species have been uncovered before.

One mystery that can't be solved with fossils, however, regards how these creatures would have protected themselves from predators. There's no evidence that they possessed any hard defensive structures. Researchers therefore speculate that they may have used camouflage in some way, or they could have been poisonous.

Yeah, that's just what we needed to hear about these ancient worms with legs that stood upright, that they were possibly poisonous too.