“You're not supposed to be in here! You're going to ruin the surprise!”The following section contains spoilers.
As the tower is made out of living flesh, the Ostrons use explosives to selectively harvest her biologically regrowable walls, under her permission and direction, to provide meat for their families and collect the blood, Temple Kuva, for other uses. Leftover shells of the walls are also used as building materials.
She is also responsible for the energy wall that envelops the Plains and keeps the Eidolons contained, and her influence protects the Ostrons' home, Cetus, from outside dangers such as the Grineer. Anyone approaching the settlement with hostile intentions would find "their transmissions silenced, their engines turned cold, and their weapons reduced to lumps of dead iron."
The Tower of Unum was one of, if not the last Orokin Tower to survive when, in the later days of the Old War, a single powerful spectral Sentient managed to land on and lay waste to Earth, the heart of the Orokin Empire. When the Tenno betrayed the Orokin, Gara stayed to protect the Tower from the Sentient.
The creature was blinded by the daylight, so it hid amongst the shadows during the day and struck the Tower at night. In desperation, the Unum instructed her followers to give her blood, Temple Kuva, to the animals living on the plains, so she could connect to them and use them to find where the Sentient was hiding and kill it before it could destroy the Tower.
The Unum's attempt backfired; the Sentient captured some of the animals and realized that the Tower's blood could restore its procreative ability, which the entire Sentient race had lost upon traveling through the Void. With this realization, the Sentient then assaulted the Tower with all of its might to seize control, replacing the Unum, and thus gaining the power to rebuild its entire race once again.
To prevent this unthinkable catastrophe, the Unum used a powerful energy barrier to trap the Sentient and gave Gara a devastating energy bomb, created from her flesh. Sacrificing herself, Gara successfully destroyed the Sentient's heart in one final battle. In the aftermath, countless pieces of the Sentient scattered about the neighboring Plains. These ghostly fragments, the mindless Eidolons, currently litter the region, appearing at night to hopelessly roam in an attempt to rebuild themselves.
- The Unum is suggested to have some forms of prophetic abilities. It is said that many rich, powerful, and influential persons had traveled to Cetus and were willing to pay a fortune to seek an audience with her, but the Unum would commune only to a few of them, regardless of their statuses or wealth.
- A piece of harvested wall can be seen being transported down to Cetus during the introduction cutscene when Tenno enters Cetus for the first time.
- Tenno can watch the meat extracting process, on the beach near the landing pad, every time they enter Cetus.
- Harvesting the Tower with explosives releases gold dust that, when breathed in, can cause a pulmonary disease known to the Ostrons as gilded lung.
- It is also known as 'The Wall' to offworlders.