residis

Residis is a fictional term used in speculative biology and worldbuilding to denote a hypothetical minimal life form or protocell. The name is derived from Latin residere, meaning to remain or stay behind, chosen to reflect its proposed role as a stable, persistent unit in models of early life.

In hypothetical taxonomy, residis are described as membrane-bound vesicles with a rudimentary metabolism and a small, self-assembling set of catalytic molecules. They lack the complex organelles found in modern cells and rely on simple energy transduction mechanisms, such as proton gradients, to drive limited biosynthesis. Reproduction is imagined as division of the vesicle rather than genetic replication with a separate genome, making the concept a useful contrast in discussions of what constitutes life.

Residis as a concept is used primarily in educational settings, thought experiments about abiogenesis, and in speculative fiction to illustrate constraints on early life and the possible continuum between chemistry and biology. It is not an empirically observed lineage or a formally recognized taxon within real biology.

In fictional works, residis may be described as inhabiting extreme or energy-limited environments, forming communities through exchange of lipids and small organic molecules, and exhibiting simple communication signals. The term serves to prompt discussion about minimal requirements for life, self-maintenance, and reproduction.

See also: protocell, abiogenesis, minimal cell, early life.