Creatures called fire rats inhabited the Mustafar environment, according to information about species. These creatures had a habit of using their teeth on the lava crystals present on that volcanic planet. Vaneé, a Sith attendant, was telling Thom Hudd, a prisoner, a story. The story involved the adventures of Spikewheel, a droid captain, and her team on Lotho Minor. Vanee compared the group's fear to the way fire rats use their teeth to chew on crystals.
The initial reference to fire rats occurred in Star Wars Adventures: Return to Vader's Castle 1. This comic issue was written by Cavan Scott and released on October 2, 2019 through IDW Publishing.