The Precambrian Worms were a species of giant, fog-dwelling, carnivorous worm from the Precambrian.
Precambrian Worms were roughly four - six feet in length, with a large, fat green body lined with large, hair-like spines, giving them a loose resemblance to sea cucumbers. The Worms were blind, but apparently had a good sense of touch and hearing. The Worms were also carnivorous, and they possessed a retractable proboscis at the front end of their body, containing a tongue lined with sharp teeth. Precambrian Worms fed through their proboscis either by attempting to swallow their prey whole or by slowly eating through their prey's flesh whle they were still alive. The Worms could also fire out a black, tar-like organic liquid from their proboscis like a projectile, probably to help locate nearby prey.
◾The Precambrian Worms came from farther back in time than any other creatures ever known to have come through the Anomalies.
◾Due to their similar physical features, some fans have speculated that the real-life prehistoric worm Ottoia was the young of the Precambrian Worms in the Primeverse. But this is unlikely, as Ottoia was an aquatic lifeform, while the Worms appeared to be land-based creatures.
◾The worms are near identical to the worms from King Kong movie (2005) which Primeval designer Daren Horley also worked on.