:keys See short keys, bent keys and odd keys.

:kickback reaction The following collision of two gliders whose product is a single glider travelling in the opposite direction to one of the original gliders. This is important in the proof of the existence of a universal constructor, and in Bill Gosper's total aperiodic, as well as a number of other constructions.

	.....O..
	......OO
	.OO..OO.
	O.O.....
	..O.....

:kidney A Gosperism for century. See also diuresis.

:killer toads A pair of toads acting together so that they can eat things. Here, for example, are some killer toads eating a HWSS. Similarly they can eat a MWSS (but not a LWSS). For another example see twirling T-tetsons II. See also candlefrobra.

	..OO.......OOO
	O....O....OOO.
	......O.......
	O.....O.......
	.OOOOOO.......
	..........OOO.
	...........OOO

:knightship Any spaceship of type (2m,m)/n. Such spaceships do exist (see universal constructor), but no concrete example is known. A knightship must be asymmetric and its period must be at least 6, which makes searching for them using programs like lifesrc very difficult.

By analogy with the corresponding fairy chess pieces, spaceships of types (3m,m)/n, (3m,2m)/n and (4m,m)/n would presumably be called camelships, zebraships and giraffeships, respectively. But no examples of these are known either, and they are even more difficult to search for.

:Kok's galaxy (p8) Found by Jan Kok in 1971. See converter for a use of this sparker.

	OOOOOO.OO
	OOOOOO.OO
	.......OO
	OO.....OO
	OO.....OO
	OO.....OO
	OO.......
	OO.OOOOOO
	OO.OOOOOO