Nasatums

Nasatums are a term used in speculative biology and certain science fiction contexts to describe a hypothetical class of ultra-microscopic symbionts associated with plant roots. In these scenarios, nasatums inhabit the rhizosphere and often the outer root tissues, forming mutualistic relationships with host plants. They are imagined as modular, simple organisms capable of exchanging nutrients, signaling molecules, and protective compounds with their hosts. They are said to enhance nutrient uptake, particularly phosphorus and nitrogen, and to increase tolerance to abiotic stress or soil pathogens. In return, plants supply organic carbon to nasatums.

The concept of nasatums is not supported by empirical evidence in real-world biology and is used chiefly for worldbuilding or theoretical discussions about microbiome interactions and the limits of mutualism. Etymologically, the term nasatum draws on Latin roots related to birth or origin and is used in plural form nasatums in most treatments.

In fiction, nasatums may be described with varied morphologies—from spherical to filamentous—and reproductive modes ranging from simple cell division to spore-like propagation. In scientific discourse, nasatums function as a thought experiment illustrating how unseen root-associated microbes could alter plant physiology and ecosystem dynamics. See also root microbiome, mycorrhiza, plant–microbe interactions.