Beyond the hierarchy of one to five-sensed beings described in the main entry, Jain cosmology posits a category of soul far more numerous and less developed than any of them: the nigoda, minute, formless clusters of souls of the lowest possible grade, existing in effectively countless numbers packed into every corner of physical space, including inside plants and other living things.
According to Jain scripture, nigoda souls exist in a state of near-total obscuration, possessing only the faintest trace of consciousness and undergoing an almost unimaginably rapid cycle of birth and death, described in some texts as many deaths and rebirths within a single breath, trapped in mutual dependence with countless companion souls within the same cluster. Jain cosmological texts hold that the total number of souls in the universe is fixed and that liberated souls, upon reaching the siddhashila, leave transmigration permanently, a departure some later texts describe as balanced by nigoda souls occasionally rising to more differentiated forms of life, though the precise cosmological accounting of this balance is treated with less uniformity than the core soul theory itself.
The nigoda doctrine performs specific theological work: it accounts for the inexhaustible supply of souls needed to fill even reduced numbers of higher life forms over cosmic time, since Jain cosmology does not permit the creation of new souls, only the movement of existing ones between states, and it grounds an extreme form of the ahimsa principle discussed elsewhere, since texts describing nigoda souls as present even in ordinary vegetable matter, water and air are part of what motivates the tradition's severe carefulness about causing harm even where none is visible.