"Crabby" is a giant crustacean sea monster that lived in the waters of Primeval's Eye. It preyed on passing boats and was presumably the cause of Dr. Yost's disappearance. When it attacked the ninja and the Sons of Garmadon, Toddler Wu gave it its new nickname, Crabby.
After Lloyd and Harumi crashed in Primeval's Eye, they used the map from Wu to try and find the location of the Oni Mask of Hatred. They boarded a boat with the insignia of the Sons of Garmadon and were attacked by Crabby along the river, snapping their boat in half. It then sailed off a waterfall. Harumi and Lloyd both survived but the boat was destroyed. Lloyd then remarked that they had made it to the Oni Temple.
Lloyd and Harumi found the mask but Harumi then revealed her true self as the leader of the Sons of Garmadon. In a standoff between the ninja and S.O.G., Crabby struck again, attacking both factions, forcing a brief alliance. Killow and Mr. E donned their masks and attacked the sea monster while the ninja used Spinjitzu on it. Zane was then able to freeze it in ice. The S.O.G. escaped with the mask and captured Lloyd. Crabby then broke out and Wu decided to name it.
The ninja and Wu tamed Crabby and brought him through Ninjago City. They gave him to a stunned policeman, who asked what to do with it. Nya told him to take it to the zoo, to which the police replied they didn't have one, while Crabby loomed behind him.
- Its design seems to be based on a crab and a lobster.
- It has a thick hide which was strong enough to break Lloyd's sword.
- Its appearance is similar to the Smoke Creature's colossal crab form from Mask of the Sensei.