Siltcrawlers, beings native to the Outer Rim world of Nelvaan, constructed subterranean dwellings by burrowing. These colonial organisms possessed the ability to hibernate. Their settlements were frequently targeted by the enormous, predatory horaxes, who would use their horn-like snouts to breach the burrows and consume the entire colony.
The initial "Horax" entry within the original Databank on StarWars.com included references to Siltcrawlers.