Rarefaction Cell

The Rarefaction Cell, or Power Cell is a key item in 's campaign which temporarily distorts gravity when used. Being heavier than any other item the Cell cannot be swallowed and weighs the player down slightly when held, resulting in a lower jump height, swim speed, and a gradual downwards slide when on poles or in tunnels while no inputs are entered.

Lore
According to Five Pebbles and Looks to the Moon, Rarefaction Cells are the emergency power systems of Iterator superstructures, allowing them to keep functioning if conventional energy sources are lost or cease to work due to entropy and decay. As the Ancients' infrastructure has decayed over thousands of cycles, the cells have become the main power source of many Iterators. The Rarefaction Cells are also the main cause of the superstructures' gravitational anomalies, distorting space and gravity around themselves while active. If they're lost or removed, the Iterator will slowly die.

Moon lost her Rarefaction Cells when her superstructure collapsed, as they were washed away by the Shoreline's ocean.

Use
The player can press and hold Shift to activate the Cell, distorting gravity for ~15 seconds and allowing for dramatically increased jump heights and swimming speed.

Bringing the Rarefaction Cell from Five Pebbles (Linear Systems Array) to Submerged Superstructure is necessary for achieving the Old Friend ending. For this reason it appears on the minimap.