Replicator
A replicator is any pattern that produces copies of itself.
Replicators occur naturally in some cellular automata. The best-known example is the replicator in HighLife (23/36). In the Replicator rule (1357/1357), every pattern is a replicator.
There exists a replicator in any cellular automaton with a universal constructor. Therefore Life, which has a universal constructor, has replicators. No concrete examples are known, however. A similar situation occurs for the rule 235/36.
External Links
Replicator at the Life Lexicon.