Bomb Slot

From Wikitroid, the Metroid wiki

A Morph Ball Bomb Slot is a device that is used to fulfill certain goals found in Metroid Prime, Metroid Prime 2: Echoes, and Metroid Prime 3: Corruption. For example, in Metroid Prime 2: Echoes, the Spider Ball Guardian can only be defeated by using Bomb Slots to change the direction of its movement so it crashes into the energy blocks. Also, the Quadraxis Final Head Module can only be destroyed when Samus rolls up into a Morph Ball and boosts onto the exposed magnetic-rail head. Samus then has to roll into one of the two bomb slots to and detonate a bomb to blow it up.

Usually, the bomb slot can be activated immediately by detonating one of the ordinary bombs, but some have to receive a power supply to make it work.