Contra Wiki
Contra Wiki
This enemy is sometimes referred to as "Sensor". For the terrain object that releases power-ups when shot, see Sensor (object). For the Super C boss, see Sensor (boss).

The Laser Controlled Nuclear Ball (レーザー制御核ボル Rēzā Seigyo Kaku Boru?) is a recurring enemy in the Contra series. It is a blinking core that acts as a weak spot on walls in the enemy bases' pseudo 3D levels.


Medium sized cores with a blinking light on their center that appear on the walls that divide the many sections of the pseudo 3D stages in Contra. They are initially found concealed behind an armored panel, but shortly afterward, they will open and expose themselves to enemy fire. All of them have to be destroyed in order to make each wall explode and have access to the next section. If they're not destroyed after a certain period of time, they'll start shooting fast-traveling projectiles at the player.

In the arcade version, they are found concealed behind a circular panel bearing the Red Falcon insignia, and they blink with purple, yellow and red lights. In the NES version, the core is mainly red and they are found concealed behind four-sectioned squared panels.

A miniboss version of this enemy turret, called Base Core, which is larger and more resilient, is usually fought at the end of these pseudo 3D stages; destroying it generally allows access to the area boss.


Neo Contra[]

Two Sensor walls appear after the climb upward in Mission 02:

  • The first one releases two hanging turrets and can fire Darrs from two side chambers; one housed underneath each sidewall (both are not properly aligned with each other). The Sensor itself is unarmed, but it is recommended to eliminate the turrets first before the Sensor in order to achieve a higher Hit Rate.
  • Immediately after the Sensor is eliminated, the commando(s) walk into a second room containing another Sensor. This time, the room houses 4 turrets and has four Darr shooters: one housed on each of the wall's diagonal corners. This Sensor is also capable of unleashing a straight firing laser beam. Damaging the sensor with enough Weapons fire will prevent it from firing.

Contra 4[]

Contra 4 marks the return of the third person corridor stages, and with them the return of the Nuclear Balls that when destroyed allow to advance through their sections. Nuclear Balls behave pretty much the same as their Contra counterparts, although some were now given a few gimmicks to make their appearance a little more interesting, such as being attached to moving panels that slowly approach toward the foreground, or one that is placed on one end of a rotating beam, forcing the player to constantly be on the move to target it.

An organic variant of the Nuclear Ball shaped like an alien eye appears in Stage 8, Alien Hive. Its behavior and purpose are exactly the same as the standard version, appearing on the fleshy walls that, when destroyed, so will the walls they were attached to, allowing the player to proceed further into the level. They look almost identically to the Shooting Eyes, although the Nuclear Balls are strictly found attached on walls, are completely stationary, and cannot attack in any way.






  • Sensors appear similar to the cores of a Defense Wall. In most appearances, it is possible that the wall's core is a Sensor.

See also[]


  1. C (LCD game) package instructions.
  2. Contra instruction booklet, page 8. (NES-CT-USA)