The Heraclitus Virus was a genetically engineered strain of pathogen created by Magos Biologis Szalin of the Adeptus Mechanicus. The virus was based on a fragment of ancient research conducted by Magos Heraclitus that was designed to increase the production of crops on Agri-Worlds. The virus was altered by Magos Szalin's genius to increase this productivity a thousandfold.
The virus was stolen by the Iron Warriors Warsmith Honsou from the Adeptus Mechanicus' experimental facility on Golbasto, killing Szalin in the attack. Honsou subsequently used this virus to destroy Tarsis Ultra in an attempt to gain vengeance upon his hated foe, the Ultramarine Uriel Ventris, who had earned great renown when he had saved that world from an assault by Hive Fleet Leviathan.
But though the Tyranids had been bested, they had still left behind a form of Tyranid flora, most likely Capillary Towers, that were slowly overwhelming the local vegetation and transforming the world's ecosystem. As the Heraclitus Virus was designed to speed up crop growth, when it was unleashed on the world from a torpedo strike it had a cataclysmic reaction with the Tyranid vegetation.
It sped up the Tyranid lifeform's growth so that it covered the entire planet and eventually consumed the atmosphere, leaving the planet an airless and sun-scoured rock, a newborn Dead World.
- Warriors of Ultramar (Novel) by Graham McNeill
- The Heraclitus Effect (Short Story) by Graham McNeill
- The Chapter's Due (Novel) by Graham McNeill