Nelvaan bruise-leech crawlers, also known as bruise-leech crawlers, were creatures resembling leeches that originated on the Outer Rim planet of Nelvaan. Before sending him to annihilate a Techno Union laboratory in the vicinity, Orvos, the shaman from the Rokrul settlement on Nelvaan, covered the chest of Jedi Knight Anakin Skywalker with bruise-leech crawlers as part of a ritual. As they moved across Skywalker's chest, the leeches inflicted pain and left blue marks.
These reddish-brown annelids, occasionally called "Nelvaan bruise-leech crawlers," were native to the Outer Rim planet of Nelvaan. Certain individuals displayed small black patches of fur near their posterior. They possessed a circular mouth equipped with teeth and two protuberances situated directly behind the head. As the crawlers moved, they had the ability to leave a blue trail behind them.
In 19 BBY, Orvos, the shaman from the Nelvaanian village of Rokrul, employed bruise-leech crawlers in a preparatory rite for Jedi Knight Anakin Skywalker before his mission to obliterate a Techno Union laboratory that was utilizing a siphon generator, which had plunged the planet into an ice age. As the crawlers slowly moved, they generated a rectangular design across Skywalker's torso with the blue trails they left behind, causing the Jedi considerable discomfort.
The animated television microseries Star Wars: Clone Wars featured the debut and sole appearance of the bruise-leech crawlers in its twenty-third episode, which was broadcast on March 23, 2005. The species' name was subsequently established in the Nelvaanian entry within the StarWars.com Databank.