"Piper Maru" is the fifteenth episode of the third season of the science fiction television series The X-Files. It premiered on the Fox network on February 9, 1996. The episode was written by executive producer Chris Carter and Frank Spotnitz, and directed by Rob Bowman. "Piper Maru" is one of those which helped to explore the series' overarching mythology. Its introduction of the black oil became a storyline milestone for the series. The black oil would later go on to play a much larger role in the series, including a pivotal role in the 1998 X-Files movie. "Piper Maru" earned a Nielsen household rating of 10.6, being watched by 16.44 million people in its initial broadcast. The episode received mostly positive reviews from critics. The show centers on FBI special agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) who work on cases linked to the paranormal, called X-Files. In this episode, a French salvage ship sends a diving crew to recover a mysterious wreckage from World War II, but the crew falls prey to a bizarre illness forcing FBI special agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) to investigate the source. Their investigation brings them face-to-face with Alex Krycek (Nicholas Lea). "Piper Maru" was written to showcase two visual images Chris Carter had wanted to include in a script "since the beginning of the show". The first of these was that of a deep-sea diver finding a still-living pilot trapped in the wreckage of a World War II-era fighter plane and the second was that of a black-and-white flashback taking place in a submarine. The title of the episode is a reference to the names of Gillian Anderson's daughter, who had been born during the production of the second season. Plot Piper Maru, a French salvage vessel, is exploring the Pacific Ocean. Gauthier, a member of the ship's crew, dives down into the sea and finds a sunken fighter plane from World War II. He is shocked to find a man alive in the plane's cockpit, with what looks like black oil in his eyes. When Gauthier returns to the surface, he has become possessed by the black oil. In Washington, Walter Skinner tells agent Dana Scully that the FBI's investigation into her sister's murder has been made inactive, despite the evidence that had been recovered. Fox Mulder tells Scully about the Piper Maru, which