A number of clades - nonsentient, presapientmodosophont, transavant, and transapient - reproduce by creating self-replicating Von Neumann devices, such as autowar seeds. If such self-replicators are left entirely unchecked, their growth rate can become exponential, consuming vast quantities of resources and leaving behind a resource desert. One of the methods used by a variety of polities to check such growth is the employment of professional spore hunters, who locate both active and hibernating Von Neumanns, and reduce their reproduction rate in one of a number of ways, from simple execution to sterilization to memetic engineering. As few such spores are transapient, this form of employment is one that has consistently been available to modosophonts, and thus has acquired a long history and become part of a variety of cultures' entertainment media.
Spore hunting is not universally accepted as being an appropriate, or even ethical, solution. Some sentient members of sporing clades view such culls as speciesism, or even outright murder of innocent individuals who merely happen to be hibernating. And, just as the line between 'unwanted spore' and 'hibernating person' is not always clear and can lead to disagreements, so can the line between 'dangerous spore' and 'personal tool'; a saying expressing this conflict is "One man's grey goo is another man's asteroid mining operation".
Spore Hunter's Day is regularly celebrated on the anniversary of either Mendel 5, 686 BT (26 Jun 1284 AD) or Archimedes 2, 593 BT (22 Jul 1376 AD), or both, in honor of a tale of ancient hunters of similar, though biological pests; or Lavosier 23, 9 AT (16 Jun 1978 AD), in honor of the earliest known virch dealing with defending against constantly-replicating invaders arriving from space.