Soronan mold is a type of mold found on Sorona. It's acidic and gives off a peppery smell. However, it has enough protein and carboxylic compounds to provide substance to terrans, though with the downside of tasting like paste. Consuming the mold also leads to tooth decay due to its acidic nature.
During the Siege of Cask, the town's colonists were forced to consume the mold to survive as the zerg laid siege. However, the mold was consumed by the attacking zerglings also, which incorporated it into their structures to become banelings, eradicating the town and its defenders. The mold became part of the genetic structure of future banelings in the Swarm, and because of this, they can survive on very low concentrations of oxygen and minimal moisture.