In the episode of the same name Jeremy created a program to finally destroy XANA and his monsters. When Odd and Aelita show up on Lyoko it appears to work. The Marabounta is a big black ooze that can consume all the monsters in a whole sector. However it confuses Aelita and the others for monsters and tries to eat them. It then tries to consume all of Lyoko itself. With it blocking the tower there is no way to get Aelita home unless it is destroyed. The warriors have to team u with Xana to hold it at bay. Odd hitches a ride on a Krab and makes it to the center of it which is a small sphere. He manages to shoot it and it is permanently destroyed. After that Jeremy never tries to recreate it again. However it is mentioned in the episode "Fight to the Finish".