The Cocoon is an AI weapon that serves as a minor antagonist in the video game; Metal Gear Solid: Peace Walker.
In 1974, the Cocoon was assigned to defend the entrance to the Peace Sentinels' Mine Base from the MSF (,Militaires Sans Frontières). The Cocoon arrived just seconds after Snake managed to defeat twelve sniper units that were guarding the facility's cargo elevator. Despite it's lack of mobility, the Cocoon proved to be a powerful weapon with it's turrets, missles, and cannon. Snake managed to decommission it for good after dealing enough damage and taking out the memory boards in the AI pod. Because of its decommissioning, the security panel of the doorway to the Mine Base's interior also ended up damaged due to some of Cocoon's fragments of armor smashing into it, allowing Snake to enter in the base.
Along with the heavy main cannon, Cocoon had the capability to launch missiles and hedgehogs (multiple spigot anti-submarine mortars modified by Huey for surface use). They take time to fully load, however, and even then, the latter weapons system cannot actually deploy its weapons systems until the lamp section activates. It was also armed with six multi-barrel machine guns; two each on both the front and back of the lower section, and two at the front of the upper section. Smaller caliber machine guns lined the left and right sides of the lower section, five on each, along with two on the upper section, at the rear and on a large three-part mechanized arm. The arm could be used to ward off enemy infantry that may position themselves beneath the vehicle or clamber aboard the outer frame, and was also equipped with a chainsaw-like attachment that would spin around in sweeping motion.
- The Cocoon is proven to be the biggest machine in Metal Gear Solid: Peace Walker.