Travist Polong was an orange, metre-long, three-eyed slug/slater-like alien that attempted to put plot into action at an hospital in Tarminster. Sarah Jane Smith showed up and he ran from her. She left to deal with a Berserker. (SJA: The Mark of the Berserker)
He later was put inside a parcel that was delivered to Sarah Jane, as she had seen it on eBay. Rani Chandra and Clyde Langer took it inside Rani's house and were attacked by Polong, who chased them to 13 Bannerman Road, where he was held back by K-9. Sarah Jane ordered Mr Smith to teleport him to Polongus, which he did. (SJA: The Wedding of Sarah Jane Smith)