Silverfish

Silverfish
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Pattern type	Spaceship
Number of cells	210108
Bounding box	11974 × 45755
Direction	Orthogonal
Period	240 (mod: 240)
Speed	31c/240 | 31c/240
Heat	125504
Kinetic symmetry	n
Discovered by	Chris Cain Dave Greene Adam P. Goucher Nathaniel Johnston
Year of discovery	2020
Rules Outer-totalistic rules B3/S23 only # of rules 20 = 1
Pattern files RLE silverfish.rle

The silverfish is a 31c/240 orthogonal spaceship that was constructed on May 8, 2020. Various reductions brought it down to its current size of 210,108 cells, which made it the smallest known spaceship of this speed, surpassing the centipede caterloopillar in cell count (and, as a result, making the smallest 31c/240 spaceship true-period again), until the construction of the Leaf bug in 2024.

History

Silverfish uses the front end design made by Chris Cain on September 20, 2014. It is a track builder with an integrated first forerake, that allows the spaceship to be relatively narrow. However, the resulting track is different from that of the previous 31c/240 Herschel-pair climber-based spaceships, which means that all other components needed to be remade from scratch to run on this new track.

A self-supporting puffer was constructed, and an engineered fuse was made on the same day as it. Put together, that was the first version of the Silverfish; originally it was extended for demonstration purposes, but when collapsed, it had a minimum population of 230,720 cells. On the following day, in a series of improvements, the unwieldy tail was replaced by one based on the Centipede's; integrated into the puffer, reducing the bounding box but not the population; a completely new tail was created and integrated, reducing the spaceship's population to 218,960 and 217,152 cells respectively. On May 13, a minor improvement was made to the tail again, with the new minimum population being 217,043 cells. On June 10, the slow salvo mechanism was improved, bringing the population to 215,338 cells, and a final improvement on June 14 replaced some of the front set's forward rakes with backward rakes positioned higher in the spaceship to decrease its length and population.

Design

Up until the last iteration, Silverfish featured the same basic design as the shield bug: a track builder in the front with a forward rake that shoots gliders onto pairs of heavyweight spaceships to turn them into sideways-travelling MWSS and support the first Herschel pair climber, followed by two identical sets of rakes that form a slow salvo to make said pairs of HWSS. Due to the backward rakes present in the final version, this analogy is no longer fully accurate.