A negative spaceship is a type of signal traveling through a periodic agar such as zebra stripes. The leading edge of the signal removes the agar, and the trailing edge rebuilds the agar some time later. The distance between the two edges is sometimes adjustable, as shown in lightspeed bubble. The central part of the "spaceship" may consist of dying sparks or even simple empty space.

October 20: FWKnightshipcompletes a redesigned (34,7)c/156 spaceship with a bounding box of (52514, 158980) and minimum population of 655,594; this is less than 1/38th of the population and less than 1/6000th of the area of the previous version of this spaceship constructed by Luka Okanishi last year.

October 10: AlbertArmstainrebuilds an initial stage from Mitchell Riley's H-to-Gs into a Herschel-to-B-heptomino converter; Lucy D'Agostinonotices that this is actually a known E-heptomino converter appended to a previously unknown Herschel-to-E converter, HRx93E -- which enables completely new Spartan Herschel conduits Rx155 and R194, among other things.

... that there is a 5 × 2 counterexample to the Coolout Conjecture, proving that patterns that are internally compatible with stability can not always be made part of a larger still life, no matter what cells are added around the edges?

... that whilst no elementary oblique spaceships were found in B3/S23 until 2018, and none have occurred naturally, at least two naturally occurring reactions have been discovered in B38/S23 that travel in an oblique direction?

... that no pattern inside a 6 × 6 bounding box is a Garden of Eden?

... that Garden of Eden patterns with only 45 live cells have been found?

... that there are orphans that are 5 cells high, but 4-cell-high orphans are impossible?

... that 6-cell-high Garden of Eden patterns were constructed as far back as 1973, but 5-cell-high GoEs were unknown until Steven Eker found some in 2016?