Skycrypt

Security spires are Forerunner structures presumably designed to contain or isolate dangerous beings. At least fourteen of these structures were located on an unidentified, icy world.

Design
The spires consist of a small, circular building located atop a long, thin pole or chain. Four fin-like structures slowly rotate around the pole directly beneath the main chamber. Given the central pole's apparent lack of structural support, the spires may employ anti-gravity technology to remain aloft.

Trivia
The Halo: Combat Evolved Anniversary multiplayer map Solitary is located within one of these spires.