Some TMNT stuff really isn't for little kids.
Eymo is an alien creature who is Anemon's partner and best friend. He resembles a small orange fish, but has a large eyeball-like appendage that can be used as an eye by other creatures.
Eymo found Anemon shortly after Anemon crashed on Eymo's planet, having been blinded when he escaped from Krang. The two formed a symbiotic relationship—Eymo allowed Anemon to see and kept him from giving in to his despair, while Anemon's great strength kept Eymo safe from the cloud-beasts that tried to eat him.
Approximately five years later, the Turtles arrived to ask Anemon to testify against Krang. They were unaware that Eymo was the one speaking to them through Anemon, concocting boasts of being a mighty sumo and claiming that Eymo had been enslaved rather than accompanying Anemon of his own free will.
However, the ruse was discovered when Anemon accidentally fell down a steep incline, and Eymo was accidentally torn from his head. Eymo quickly returned to his friend, just in time for Anemon to defeat another cloud-beast. After Eymo expressed a wish to leave his planet for a time, the two agreed to come to Krang's trial.
During the trial, Eymo was required in order to read an old employment contract that Anemon had previously signed. When Hakk-R attacked, he effectively rendered Anemon helpless by tearing Eymo from his head, but the two managed to reunite, allowing Anemon to immobilize Hakk-R with his formidable strength.