Parabiosis
Appearance
Parabiosis is the surgical act of artificially creating conjoined twins of two organisms.[1]
This has been displayed on TV shows such as The Simpsons "Treehouse of Horror VII" where Hugo (Bart's evil twin) sews a rat and a mouse together in the hopes of learning how to reattach Bart to himself successfully. The Russian electronica artist Nybraz has a song with this title.