Muckrats were a species of rodent that inhabited the galaxy. During the Iron Blockade, the Galactic Empire's attempt to prevent the Anoat sector's populace from learning of the crushing Imperial defeat at the hands of the Alliance to Restore the Republic in the Battle of Endor, the Aqualish Roonlo sent muckrat skulls to the human Riley on a monthly basis. According to Riley, the skulls were a display of his hatred for her, but when Riley's sibling confronted Roonlo, the Aqualish claimed that the skulls were merely tokens of affection.