An object is said to be endemic to a rule if it can only exist in that rule, i.e. if no change in the rule's birth and survival conditions supports the object. The term is understood to be relative to a certain class of cellular automata, e.g. outer-totalistic Life-like cellular automata or isotropic non-totalistic Life-like cellular automata.
- Rhombic (November 18, 2017). Re: Miscellaneous Discoveries in Other Cellular Automata (discussion thread) at the ConwayLife.com forums
- Endemic periodic patterns and still lifes (discussion thread) at the ConwayLife.com forums