Breeder (cellular automaton)

In cellular automata such as Conway's Game of Life, a breeder is a pattern that exhibits quadratic growth, by generating multiple copies of a secondary pattern, each of which then generates multiple copies of a tertiary pattern.

[1] Breeders can be classed by the relative motion of the patterns.

The classes are denoted by three-letter codes, which denote whether the primary, secondary and tertiary elements respectively are moving (M) or stationary (S).

The four basic types are:[1] A spacefiller (which also undergoes quadratic growth) may be thought of as a fifth class of breeder.

However it differs from a true breeder in that it expands a single island of cells, rather than creating independent objects.