Retriever Sentinel

The Strato-Sentinel is a Forerunner Sentinel variant. They were designed to perform terraforming projects, such as strip mining the resource moon located in the middle of Installation 00. They were also used to help in the construction of the Halo rings, such as the newly constructed Installation 04. They were also used during the construction of the Portal on Erde-Tyrene, in the present-day country of Kenya.

Trivia

 * Strato-Sentinels were originally planned to appear in Halo 3, but were cut from the game.
 * The word "Strato" in the Sentinel's name is most likely derived from Latin, as "strato" is the ablative form of "stratus", meaning "stretched out" or "extended".

List of appearances

 * Halo 3: The Cradle of Life
 * Halo Legends
 * Origins