This is the Apsyrtus class Mine. It specialized to increase the number of enemy casualties when an Operation Phoenix battle fleet is on retreat.
When the fleet is on retreat, thousands of these small warheads will be released from launchers built into the aft section of every ship involved in Operation Phoenix. These mines are outfitted with the ETS3-FLXand the Advanced Daemon Re-Enforced Armour's optical stealth system, allowing them to claim their victims without giving them the chance to react.
After they are released, they use their small gravimetric drive system to approach a target and attach themselves to that target. The fusion warhead will then wait until there is a high probability of multiple enemy ships being distroyed/disabled by the blast and then it will detonate. The warhead also has a time delay so that if it hasn't detonated 1 hour after it is launched, it will detonate.