One member of the species was attracted to the heat and light produced by Toa Mahri Jaller's sword during the Toa Mahri's escape from the undersea caves the Barraki put the Toa in. Ever since then, it followed him. Upon seeing it, Jaller wondered if he had seen Toa Mata Tahu the same way when he had first arrived on Mata Nui.
The crab saved Kongu from a vampiric sea squid by ripping the organic creature apart. It also distracted Mantax by firing a Cordak blaster, allowing Jaller to close in on both the Barraki and the Ignika.
When the Toa Mahri were teleported back to Metru Nui, the Crab was left behind.