Futurama: The Wild Green Yonder

The Planet Express crew visits Amy's parents, Leo and Inez, who are destroying the "old" Mars Vegas and constructing a more extravagant one. A group of eco-feminists, led by Frida Waterfall, protesting the destruction of the environment, leads to an accident wherein a piece of Frida's jewelry lodges inside Fry's brain granting him telepathy. The destruction upsets Leela, but Leo asserts that he has received environmental clearance from a bribed Professor Farnsworth. Unconvinced, Leela saves a Martian muck leech, the last of its species, from the site.Hutch, a transient Fry stumbles upon, advises him to wear a tin foil hat to keep other people's thoughts out of his head and warns Fry never to reveal his powers and to beware the "Dark Ones".While golfing with the crew, Leo reveals his plan to destroy 12% of the galaxy and build the universe's largest miniature golf course. Farnsworth and the crew survey the site and discover an asteroid in a violet dwarf star system, teeming with primordial life forms. Over Leela and Fry's objections, Farnsworth approves Leos project causing Leela to join the eco-feminists.Hutch introduces Fry to the "Legion of Mad Fellows", a secret society of other tin foil hat wearing telepaths led by the No. 9 man. Fry learns that the violet dwarf is the only surviving egg of the Encyclopods, a now-extinct species which evolved to preserve the DNA of all endangered life forms and recreate extinct species, whilst the Dark Ones evolved to pursue the destruction of all life. Due to a resurgence in the life-giving force "Chi", the Encyclopod will soon be reborn. As Fry is immune to the Dark Ones' psionic powers he alone can save the star.Leo enlists Zapp Brannigan and Kif Kroker to capture the eco-feminists and Fry infiltrates Leo's empire as a security guard. Fry later runs into Frida and has her take a discreet message of support to Leela, but an unseen Dark One later murders Frida. Farnsworth, Zoidberg and Hermes are captured by the eco-feminists (now joined by Amy, LaBarbara Conrad and others), who commandeer the Planet Express ship. Fry and Leela arrange a rendezvous which is ambushed by the eavesdropping Zapp in the Nimbus. The eco-feminists are captured and sent to prison.At a Legion meeting, No. 9 explains that Fry must not only stop the implosion of the violet dwarf, but also identify and thwart the Dark One who is sure to be present. Though no one knows the current form of the Dark One, its mind cannot be read, allowing Fry to identify it. No. 9 gives Fry the Omega device, which can disable the Dark One at close range.Bender arrives to free the eco-feminists from prison and Hermes, Zoidberg, Scruffy and a repentant Farnsworth arrive in the Planet Express ship and whisk them off to stop the implosion ceremony.At the ceremony Fry is unable to locate an unreadable mind in the massive audience and concludes that he must be the Dark One. The Eco-Feminists disrupt the ceremony and Leela stops Fry from imploding the star. Fry activates the Omega Device and Leela's leech reveals itself to be the lone surviving Dark One before collapsing. The violet dwarf system forms a giant sperm and flies into the star, creating an Encyclopod embryo which quickly reaches adult form. The Dark One kills Hutch, his dying act is pulling Frida's necklace out of Fry's forehead causing Fry to lose his telepathy. Zoidberg eats the Dark One and the Encyclopod preserves Hutch's DNA before flying off.The crew of the Planet Express ship and the Eco-feminists escape. Fry and Leela profess their love for each other as the Nimbus chases the Planet Express ship toward a wormhole which the Professor warns could take them trillions of light years away with no way of knowing if they could ever return. Everyone unanimously agrees to go for it. Fry and Leela kiss as the ship enters the wormhole in a flash of blue lights similar to the show's opening sequence.

Question: What does Leela save?
Answer: Martian muck leech