Exo-Toa

Exo-Toa were special suits of powered armor that were invented by the Nynrah Ghosts. Toa and other similarly-sized beings could wear and control them, or they could be programmed to act on their own as robotic sentries.

After the Makuta species "evolved" from biomechanical form to a purely gaseous state, Chirox took over an Exo-Toa to 'demonstrate' to Mutran the new powers being made entirely out of antidermis exhibited. Exo-Toa were one of the kinds of things Makuta could possess along with other robots, such as Maxilos. Later, when Mata Nui fell into his deep sleep, the resulting Great Cataclysm ruptured a Makuta's armor, and needed to be placed in an Exo-Toa suit in order to remain alive.

In the time of the Toa Hagah, the Brotherhood of Makuta used Exo-Toa as part of their army, which also included Visorak, Fohrok and their Dark Hunter allies.

The Bohrok War
Thousands of years later, when the Bohrok swarms were awakened by Teridax to attack the island of Mata Nui, the Toa Mata ventured into the Bohrok Nest to confront the swarms' twin queens. Travelling through the tunnels deep below the island's surface, the Toa discovered a chamber containing six Exo-Toa. Each Toa stepped into one of the suits, which they then attempted to use when they encountered the Bahrag. However, Tahu found that the electro-rockets had no effect on Cahdok and Gahdok; even worse, the armor hindered the Toa from using their elemental powers. Only by abandoning the suits were the Toa able to successfully defeat the Bahrag.

The Bohrok-Kal Crisis
Later, when the elite Bohrok-Kal tried to free the Bahrag, the now-Toa Nuva followed the Bohrok-Kal into the Nest; there, they found the six Exo-Toa fighting the Kal on autopilot. However, the battle was a short one, and the Exo-Toa were reduced to scrap metal. However, after a last-minute gambit on Gali's part, the Bohrok-Kal's powers spiraled out of control; Gahlok-Kal, whose power was Magnetism, ended up drawing the Exo-Toa pieces toward itself, crushing the Bohrok-Kal under the wreckage. Later, Nuparu, an Onu-Matoran Engineer, salvaged the scrap, intending to study it; however, he had little time to do so before he and five other Matoran embarked on a journey to Voya Nui and subsequently became the Toa Inika.

Reign of Makuta
During Teridax's reign, Exo-Toa were used by Makuta to hunt down and apprehend fugitives and return them to Metru Nui. One such army of Exo-Toa attacked Tahu's team in the ruined land of Karzahni; fortunately, Onua arrived in time to save them, and destroyed the robotic suits with an earthquake.

It remains unknown what became of the remaining Exo-Toa after Makuta was finally struck down during his battle with Mata Nui.

Set Information

 * The Exo-Toa's set number was 8557.
 * The Exo-Toa consisted of 360 pieces.
 * The Exo-Toa set would actually only allow four Toa Mata sets to fit into it: Tahu, Gali, Lewa and Kopaka. Because of Pohatu's upside-down torso, he couldn't fit in one. Onua was also unable to fit concerning his "head placement" on his set. However, with a few minor alterations, you can reconstruct Onua and Pohatu to fit in the Exo-Toa armor.
 * Stars Tahu also cannot fit in the Exo-Toa, despite the set being an updated set version of his Toa Mata Form.