doubted that the network would continue the show without him, saying: "I think [Nickelodeon executives] respect that my contribution is important. I think they would want to maintain the original concept and quality." Consequently, he resigned as the showrunner and appointed his trusted staff member Paul Tibbitt to the role. Although he no longer had a direct involvement producing SpongeBob SquarePants, he retained his position as an executive producer and maintained an advisory role, reviewing each episode. Tibbitt started out as a supervising producer but rose up to executive producer when Hillenburg went into semi-retirement in 2004. While he was on the show, he voiced Potty the Parrot and sat in with Derek Drymon at the record studio to direct the voice actors while they were recording. During the fourth season, Tibbitt took on voicing for Potty, while Andrea Romano replaced the two as the voice director. In 2014, Tibbitt announced on his Twitter account that Hillenburg would return to the show. However, he did not specify what position the former showrunner would hold. As early as 2012, Hillenburg had already been contributing to another film based on the series, which was first reported in 2011 and officially announced the following year, with Tibbitt as director. Tibbitt also wrote the story with Hillenburg, who "[had] been in the studio everyday working with [the crew]." Besides writing, Hillenburg also executive-produced. He said in 2014: "Actually when [the film] wraps, I want to get back to the show. ...it is getting harder and harder to come up with stories. So Paul [Tibbitt] and I are really going to brainstorm and come up with fresh material." Called The SpongeBob Movie: Sponge Out of Water, the second film adaptation was released in 2015 to positive critical reception, currently holding a Rotten Tomatoes approval rating of 80 percent and an average rating of 6.5/10. It earned $323.4 million worldwide, becoming the second highest-grossing film based on an animated television show, behind The Simpsons Movie (2007). Other pursuits In 1998, Hillenburg formed United Plankton Pictures Inc., a television and film production company, which produces SpongeBob SquarePants and related media. From 2011 to 2018, the company published SpongeBob Comics, a comic-book series based on the cartoon. Hillenburg announced the venture in a 2011 press release, where he said, "I'm hoping that fans will enjoy finally having a SpongeBob comic book from me." Various cartoonists, including James Kochalka,