The Piranha deploys unpowered conventional bombs en masse, relying on momentum to deliver the payloads. The maximum damage potential is extreme, but most targets can either avoid or shoot down many of the bombs.
The first bomber most new players will encounter due to being widely used by pirates. A full salvo impact will deal horrific damage, comparable to a Reaper-class Torpedo. Fortunately they can generally be dodged by nimble ships or alternatively the bombs shot down by high rate of fire, high damage point defence such as Vulcan Cannon.
Actually surprisingly decent against stations, as the large number of bombs can very easily overwhelm point defences, and the chance of missing is reduced immensely by attacking a stationary target.