BETA Hives
The bases of the BETA are called Hives, gigantic semi-organic structures built into the land. The excavated underground structure is the primary facet of the Hive; it is where the BETA stay and wait when not out in the field, and the deepest part of the main shaft is where the Hive Reactor is located.
Hives are classified into different phases according to their size; the number of BETA per Hive increases in proportion to how far a Hive has developed within a Phase. The amount of time it takes a Hive to move to the next phase varies depending on the Hive. The largest hive on Earth is the @Kashgar Hive, Objective 01, a Phase 6 Hive, while the largest Hive confirmed by mankind is a Phase 9 Hive on Mars. There are also numerous Hives on the moon.
Hive Terminology
Monument - The only part of a Hive raised on the planetary surface. Construction of the monument begins at Phase 2 during a Hive's development, eventually reaching to 1 kilometer in height. At high Phases it also gains the capability to fire objects into orbit, acting much like a catapult. Monument appearance is like jagged piles of shale or ore.
Stab - Overarching name for the entire underground structure of a Hive. It consists of the main shaft extending out into the drift tunnels and the main hall.
Gate - Openings on the planetary surface that lead into the Hive. They are created within 20 hours of Hive creation, and signal the beginning of Phase 1 development for the Hive. They are the means by which TSFs enter Hives during assaults.
Drift - Tunnels that extend out from the main shaft in all directions towards the surface, used by the BETA as underground pathways from the center of the Hive. The extent of drifts grow over time and alongside BETA activity, resulting in sleeper drifts. A sleeper drift is a drift in the hive's stab that has been sealed off by a thin material. Much like a sleeper shaft, it is believed that they were sealed off during the process of hive expansion.
Shaft/Main Shaft - The typical shaft is a tunnel used to connect the halls between drifts. The shaft above the main hall is a special type known as the main shaft, and constructed since the beginning of the Hive's existence. The main shaft serves as the center of the entire stab, and also has a purpose in launching mysterious objects out of the Hive and beyond Earth's orbit. A sleeper shaft is a shaft in the hive's stab that has been sealed off by a thin material. It is hypothesized that they are tunnels that became unneeded with the expansion of a hive and were closed as a result.
Hall/Main Hall - Halls, the construction of which begins at Phase 2, are enlargements in a segment of a drift, sometimes serving as junctions in drift tunnels, that are typically used for preparatory storage of "inactive" BETA. For that reason, Hive assault operations will typically endeavor to avoid venturing through halls. The main hall is, like the main shaft, of a special make; it is the central part of a Hive, located at the very end of the main shaft, and is where a Hive Reactor can be found at.
Hive Development Phases
Phase 1 - For the @Kashgar Hive, Objective 01, Phase 1 was achieved within 20 hours of the landing unit touching down. The gates and the main shaft were constructed, while the newly activated BETA invade the surrounding area at the same time. The Hive Reactor would later be unloaded into the bottom of the main shaft. However, it is not yet understood how the Earth-born Hives achieve and bypass this initial phase.
Phase 2 - The main hall and drifts are constructed. The monument first begins construction at this Phase, and can reach up to 50 meters tall. The main shaft now extends 350 meters downwards from ground level and is 100 meters in diameter at its largest point. The stab extends for 2 kilometers around the Hive, while the BETA begin reshaping an area of 30 kilometers around the Hive, destroying 50% of the regional vegetation in the process.
Phase 3 - The Hive has almost doubled in size during this phase. The monument is now 100 meters tall, and an opening has been constructed at its top, exposing the main shaft to the open sky. The main shaft itself now extends 700 meters downwards from ground level, and the stab extends for 4 kilometers around the Hive.
Phase 4 - A Hive is considered Phase 4 when the largest segment in its main shaft has achieved 200 meters in diameter. The monument is at or above 300 meters tall, and the main shaft now extends 1.2 kilometers downwards from ground level. The stab extends for 10 kilometers around the Hive, while BETA activity has almost completely flattened 40 kilometers of land around the Hive; the only exception are any volcanoes in the vicinity.
Phase 5 - The monument is 600 meters tall. The main shaft now extends 2 kilometers downwards from ground level, and the stab extends for 30 kilometers around the Hive. Once a hive reaches Phase 5, it can launch objects up into space. Mankind has been unable to determine just what those objects are, and can only tell from the trajectory that their destination is outside the solar system. (It is later revealed by the BETA Superordinate that said objects contain resources, which would probably include G-Elements due to their unique attributes.)
Phase 6 - The monument is 1 kilometer tall. The main shaft extends 4 kilometers downwards from ground level, and the stab extends for 100 kilometers around the Hive. It took about 27 years for the @Kashgar Hive, Objective 01, the only example of a Phase 6 Hive to have existed on Earth as of 2001, to reach this Phase grade.
Brain Pods
A bio-organic structure used by the BETA to house the extracted brains of captured humans within a Hive's Main Hall, first encountered in the aftermath of Operation Lucifer, during cleanup operations. The extent of the pod's functionality and how it maintains the well-being of the exposed human organs is unknown, but it is in some way connected to, and powered by, the Hive's Reactor. The humans, despite being broken down to only their brain and spinal cord, are kept alive and fed various stimuli at the BETA's discretion. Dreaming has also been a noted phenomenon the brains can experience, and in some way @Human ESPers are able to share and communicate thoughts with their human consciousness in this suspended state.
These pods are often arranged in collections of columns, made of rock and other hive building material, with the brains themselves resting near the center of the column, high above the hall's floor.
Some pods have been interred with human remains that include more than simply the brain and spinal cord, such as full upper torsos. They appear to be doubling as a type of storage, with the process of breaking down the body to mere organs already in progress.
Pods have also been observed capable of being "powered down", as seen in the aftermath of the Yokohama Hive's takeover during Operation Lucifer. The blue luminescent material was seen to have dimmed considerably from its usual bright glow. These represent humans that have either had their life support "shut off" by the BETA on purpose, through external events (such as stress on the powering Reactor during said battle), or simply that the pods were not enough to keep the humans from expiring on their own.