Little is known of the smaller variant used by Covenant troops to breach UNSC vessels, though the larger variant has been seen close-up. The charge's appearance is that of a long bulbous shape with many spikes protruding from it. It has a central control hub located at the top of the bomb. It utilizes the annihilation of matter and antimatter to create a massive explosion. Nearly 100% of the energy in the matter is released in the explosion, in contrast to the mere 7% released by a UNSC nuclear fusion warhead.
The bombs were used by the Covenant during an operation that was being conducted by the SPARTAN IIs. One of the Spartans, Solomon-069, was lured onto a Covenant Battlecruiser and subsequently killed when an anti-matter charge aboard detonated.
These weapons were used during the Battle of Earth to assault Earth's Orbital Defense Platforms. The boarding parties delivered the ordnance and destroyed Athens Station and Malta Station. The bomb that was on Cairo Station was secured by John-117 and Cortana; John-117 later performed a micro-gravity maneuver to deliver the device to a Covenant Assault Carrier with shields down and a fresh 'hole' created by a pair of Longswords. John entered the hole and detonated the bomb in the core resulting in the destruction of the Carrier.
- Jason Jones of Bungie referred to the bomb as the "Giant Covenant Space Pickle."
- The bomb was not originally going to be included in Halo 2. Instead, there would be a level called Covenant Ship, where John-117 would board the Covenant Assault Carrier and destroy it from within, but due to deadlines, the level was cut and Bungie decided to add the bomb.
- It is not likely that the entire bomb was filled with antimatter as the explosion would be inconceivably large. It is more likely that the bomb is so bulky because the antimatter must be kept in a vacuum and kept from touching the walls via force field. Even with the Covenant's superior Energy shield technology, it is understandable that they would add as many fail safes as possible due to antimatter's extremely volatile nature when it contacts normal matter.
- The bomb, during Halo 2, had exactly 7 seconds left on the timer. This can be figured out by timing how long it takes to blow after John-117 reactivates it on the Covenant Carrier.