Gosper glider gun

The Gosper glider gun was discovered by Bill Gosper in November 1970, and is the first (not to mention, the smallest) gun found. Through glider synthesis, this could be created from eight gliders and destroyed by five gliders.

Discovery
The search for the glider gun came as a result of a $50 question posed by Conway in 1970.

Here is a snippet of the challenge from a paper published in 1970 describing the Game of Life:

''"Conway conjectures that no pattern can grow without limit. Put another way, any configuration with a finite number of counters cannot grow beyond a finite upper limit to the number of counters on the field. This is probably the deepest and most difficult question posed by the game. Conway has offered a prize of $50 to the first person who can prove or disprove the conjecture before the end of the year. One way to disprove it would be to discover patterns that keep adding counters to the field: a "gun" (a configuration that repeatedly shoots out moving objects such as the "glider," to be explained below) or a "puffer train" (a configuration that moves but leaves behind a trail of "smoke"). I shall forward all proofs to Conway, who will act as the final arbiter of the contest." ''