Alien Power Cell (Fallout 3)

Energy cells of extraterrestrial origin. Alien Blaster uses this type of ammo.

120 shots can be found next to the spaceship. Some more are in Fort Independence, lower level, outcast weapons room.

You can also find an Alien Blaster and a bunch of ammo under a statue near Tepid Sewers. There is also some ammo located further west in the immediate area of the LPB broadcast tower to the west of the crash site.