also is used in the TV series as the backing for a Sirius Cybernetics Corporation robot commercial (slogan: "Your plastic pal who's fun to be with!"). So Long, and Thanks for All the Fish After mice, the second most intelligent species on Earth were the dolphins. The line was also the title of the fourth book in the trilogy, and appears in that book as a message inscribed on crystal bowls left as parting gifts from the dolphins to the human race. Its popularity was such that it was the title of the opening song for . The phrase was spoofed for the 1997 NOFX album So Long, and Thanks for All the Shoes. The phrase was also spoofed for the All Time Low track "So Long, and Thanks for All the Booze", from the appropriately-titled album Don't Panic. This is also the title of a track by A Perfect Circle on their 2018 album Eat the Elephant. At their concerts this track was dedicated to the people in the crowd who knew where their towels are. Also, the video features flying dolphins in reference to HHGTTG. In the 2020 video game Factorio, there is an achievement titled "So Long, and Thanks for All the Fish", which is achieved by launching a raw fish into space. See also 42 (number) Apophenia Meaning of life Somebody Else's Problem References Further reading The Hitchhiker's Guide to the Galaxy Hitchhiker's Guide to the Galaxy Riddles