Cymotes were purple and parasitic species that were presumed to have died out millennia before the Galactic Civil War occurred. These creatures, viewed as a terrifying and ghastly menace, implanted their eggs inside the mouth of a living being, with the offspring consuming their way out upon hatching. Despite their fragile bodies beneath their protective shells, they were considered palatable. The unconventional archaeologist Doctor Chelli Lona Aphra claimed they were a common decorative element on the tableware of the ancient Merelithic civilization. In 3 ABY, a number of cymotes, defying their presumed extinction, were found on the luxury cruiser Opal Empress as it transported Ebann Drake to what he described to his relative Domina Tagge as an incredible opportunity.
Subsequently, Tagge dispatched Aphra and the smuggler Sana Starros to find Drake and ascertain the nature of this opportunity. However, by the time they reached the Opal Empress, the cymotes had killed every passenger on board, including Drake. As Aphra and Starros navigated the ship, they noticed the deceased passengers, unsure of the cause of death. The pair proceeded to a cabin to locate Drake, when Aphra detected noises emanating from the vents, which she didn't know were from the cymotes. Aphra inquired with Starros if she had also heard the sounds, but the noises ceased when Starros questioned her about them. Ultimately, they discovered Drake's body and the nature of his significant opportunity: an invitation to a Crimson Dawn auction where they intended to sell the smuggler Han Solo. While Starros and Aphra discussed the auction, they were attacked by the bounty hunter Durge, who had arrived to collect a bounty on Drake.
As Aphra and Starros conversed with Durge, the cymotes emerged from the vents and attached themselves to him. Although he managed to remove them, the trio then entered a room. Aphra recognized the creatures and informed Starros about the threat they posed. After Aphra mentioned their supposed extinction, Durge retorted that he could rectify that. Starros inquired about the cymotes' weaknesses, and Aphra revealed their susceptibility to atmospheric changes. In response, Starros proposed expelling them through an air lock, and they began moving towards one. Durge lured the cymotes into the air lock, but Aphra also ejected him into space along with the cymotes. Due to the rapid decompression, the cymotes exploded upon exposure to space.