"The Mizukage, the Giant Clam, and the Mirage" (水影と蜃と蜃気楼, Mizukage to Ōhamaguri to Shinkirō) is episode 300 of the Naruto: Shippūden anime.
Before Gaara can completely seal the Second Mizukage and the Third Raikage, theyescape and begin ruthlessly attacking the Fourth Division. Meanwhile, the battle between Ōnoki and Mū drags on with none being able to get the upper hand on the other using the Dust Release: Detachment of the Primitive World Technique. Mū warns his pupil to call for assistance as the situation did not look good for his aged disciple. As the Mizukage and Raikage reveal their abilities and how to counter them, the Mizukage summons his Giant Clam and the Third Raikage breaks away from him with a group inclusive of Temari follow him. Gaara leaves the sealing of the Mizukage up to the members of his division and opts to go after Mū instead, greatly offending the Mizukage. During the battle with the Tsuchikage, Naruto arrives and uses his Planetary Rasengan, and with Gaara's assistance is able to land a hit on Mū sending the Tsuchikage flying. Ōnoki quickly uses his Earth Release: Added-Weight Rock Technique to weigh Mū down to the point that he cannot move at all, and Gaara subsequently seals him. Gaara immediately questions Naruto as to why he is on the battlefield just as Shikakuspeaks to them and explains why Naruto was there. Gaara asks Naruto if he can handle using the Nine-Tails' chakra so easily, and he answers that he doesn't plan to die until becoming the Hokage, and is not a kid just because Gaara is Kazekage. Mobilising to where the Third Raikage was, the two Kage head over to confront the Second Mizukage. The shinobi there are still struggling to defeat the Second's Demonic Illusion: Steaming Multistoried Building, and are attacked by his Water Balloon Technique before Gaara rescues them. However, the oil in the technique keeps weakening his sand as Gaara engages the Second. Elsewhere his sensory sand locates the real Giant Clam which Ōnoki then tries to destroy, but he doesn't have enough chakra to use his Dust Release. He instead uses a weightedstone fist to break the clam's shell thus dispelling the mist. However, Ōnoki strains his back, allowing the Second Mizukage to use his Water Gun Technique to shoot the Tsuchikage before he can escape.
The shinobi who insulted the Mizukage's facial hair for the second time bears a striking resemblance to Kurotsuchi.