|View static image|
|Number of cells||4|
|Year of discovery||1970|
Grin is a common parent of the block. Its name derives from the Cheshire cat, an 18-cell six-tick grin predecessor created by C. R. Tompkins that appeared unaccountably both in Scientific American and in Winning Ways.
|Cheshire cat, leaving a block as its pawprint|
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In other rules
Grin is a common lightspeed spaceship in many Life-like cellular automata, for example Seeds and Live Free or Die. It is the third most common spaceship in the former, where it is known as moon. In isotropic non-totalistic cellular automata, it works from B2ae/S to B23-j45678/S01e2-k345678.
The pattern also appears as a c/2 orthogonal spaceship in some B0 rules,[which?] interestingly keeping the same appearance in all phases.