Two-glider octomino

From LifeWiki
Jump to navigation Jump to search
Two-glider octomino
x = 4, y = 4, rule = B3/S23 2b2o$2b2o$3o$bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]]
Pattern type Methuselah
Number of cells 8
Bounding box 4 × 4
Lifespan 386 generations
Final population 48
L/I 48.3
F/I 6
F/L 0.124
L/MCPS 48.3
Discovered by Unknown
Year of discovery 1971

The two-glider octomino[n 1] is a fairly common methuselah that stabilizes into four beehives and two traffic lights after 386 generations. It is so named because it can be formed by a particular 2-glider collision, shown below.

x = 11, y = 10, rule = B3/S23 8bo$8bobo$8b2o5$3o$2bo$bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 3 ZOOM 24 HEIGHT 450 THEME Book GPS 5 AUTOSTART T 0 PAUSE 3 T 11 PAUSE 2 LOOP 12 ]]
The 2G collision that makes the two-glider octomino[1]
(click above to open LifeViewer)


x = 6, y = 5, rule = B3/S23 bo$2o$bo$4b2o$4b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ X -1 Y -1 AUTOSTART GPS 6 LOOP 15 T 0 PAUSE 1 T 14 PAUSE 1 ]]
(click above to open LifeViewer)
RLE: here Plaintext: here
x = 33, y = 6, rule = B3/S23 bo$o11bo9bo9bo$o10b2o8b2o8b2o$o8bo10bo9bo$o9bo8bo9bo$o9bo8bo10bo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART GPS 3 LOOP 4 T 0 PAUSE 1 T 2 PAUSE 1 T 3 PAUSE 0.7 ]]
(click above to open LifeViewer)
RLE: here Plaintext: here

Shown are an easily edgeshootable six-cell pattern whose great-grandchild is the two-glider octomino and three six-cell patterns that are uncles of the two-glider octomino (i.e. their grandchild is the same as the two-glider octomino's child). The latter six-cell pattern can be created through a T-tetromino or other traffic light predecessor interacting with a block.


After initially expanding downwards and then in various directions, the octomino drops a toad at generation 21. Meanwhile, the region on the other side has become a traffic light predecessor. The region that dropped the toad starts moving in the opposite direction, drops a block predecessor, then starts interacting with the traffic light. The resulting region continues moving, edgeshoots a block, then heads downwards. This lasts until generation 69, by which point the second block has been destroyed. c/2 downards movement resumes at generation 99, and at generation 106, a traffic light predecessor is edgeshot. The c/2 forwards movement ends at generation 110.

At generation 114, one group of chaos starts to move towards the block and toad. At generation 124, it destroys the block. This temporarily halts its movement, but it resumes around generation 139 and destroys the toad at generation 153, by which point half of the traffic light has been destroyed. From generation 166 to generation 183, three traffic light predecessors form and are destroyed. At generation 203, the first object that survives to the end, a beehive, is formed on the side from the region that destroyed the toad.

At generation 276, a pond is formed from the remaining half of the traffic light from generation 117. At generation 283, the second surviving object, another beehive, is formed. At generation 285, a block, a toad, and a honey farm predecessor form. Three-quarters of the honey farm are destroyed upon hitting the block and toad, but the last beehive survives some time longer, until generation 331, at which point it is destroyed. One generation later, a traffic light predecessor that was created at generation 320 finishes developing, which will survive to the end. Another traffic light also forms at the same time, but starting at generation 337, it is destroyed by various chaos. The resulting mess spawns the third surviving beehive at generation 350. Meanwhile, at generation 354, an R-pentomino starts interacting with the mess, causing it to form a traffic light at generation 385 and a beehive at generation 386, at which point the pattern stabilizes.


See Two-glider octomino hasslers for a list of oscillators that hassle the object.

Use in conduits

The Two-glider octomino is a recognized conduit object, represented by the letter O.


a two-glider octomino about to be eaten by a fishhook

The two-glider octomino can be eaten using a variety of methods. One of the simplest and quickest requires a single fishhook, which finishes eating the two-glider octomino after only nine-generations.


As noted by Emerson J. Perkins in 2011, the octomino appears to move diagonally at the speed of c/39 on an 11 × 11 torus.[2]


  1. Sometimes simply called the octomino despite this being an ambiguous term due to the existence of 368 other octominoes.
  2. Ash on Catagoluehere

See also


  1. The 5 methuselahs buildable from 2 gliders at Mark D. Niemiec's Life Page (download pattern file: 0/7oo.rle)
  2. Emerson J. Perkins (July 4, 2011). Re: New ideas for pattern types (discussion thread) at the forums

External links