Energy cell (Doom)

The cell is the unit of ammo used by the plasma rifle and BFG 9000. Each BFG shot consumes 40 cells, while the plasma rifle can be fired one cell at a time (although this takes some concentration, as its rate of fire is very high).

Perhaps confusingly, the games' instruction manuals show "Cell" as an ammo pickup. This pickup actually contains 20 cells (40 at I'm Too Young To Die and Nightmare! skill levels), and the game calls it an energy cell. Other sources call this pickup a cell charge.