## Symmetrica / Spaceships

The most common spaceship is the tugboat, followed by the schooner. There are many other natural and semi-natural spaceships, but all of them are rare.

All (semi-)naturally occuring spaceships move at a speed of c/2 orthogonal. There is, however, a natural 5c/19 puffer — the mason — which can be modified to produce a 5c/19 spaceship, the slowpoke. Moreover, several spaceships at non-standard speeds (including diagonal speeds) have been discovered with the help of the search program ikpx2. The diagonal speed limit for spaceships in Symmetrica is c/3 (see hawk for an example), faster than that in the Game of Life.

In Symmetrica, one can unambiguously refer to spaceships as “ships,” because the object known in the Game of Life as ship does not exist.

### Tugboat

• Period-2 c/2 ship
• Smallest and most common ship

Tugboats can be stacked indefinitely as shown below. The resulting period-2 ships are known as “tugboat chains.”

Here is a view of every head-on tugboat collision:

### Schooner

• Period-2 c/2 ship
• 2nd most common ship

The schooner can eat blinkers and flares, and can be eaten by a block.

Since the schooner looks similar to the tugboat, but with an additional “blinker,” one might wonder whether further “blinkers” can be added, resulting in new spaceships. This is in fact possible, as long as the sides of the ship are stabilized with tugboats. How exactly the stabilization is done depends on the value of the number of “blinkers” modulo 4.

Note: there are many, many period-2 ships in Symmetrica — far too many to list here. See this Catagolue page for more period-2 spaceships.

### Cat

• Period-4 c/2 ship
• One phase contains a 32-cell polyomino

The tugboats on either side can be replaced with schooners or tugboat chains.

### Cyclops

• Period-4 tagalong for two tugboats or schooners
• Six variants are shown

### Goalpost

• Period-4 c/2 ship
• Back section has a period of 2, and resembles two tugboats fused together.

A variant of the goalpost replaces the “tugboats” in the back with “schooners”:

The goalpost is extensible, and allows middle sections to be wider than their neighboring sections. (Compare the overweight spaceship from the Game of Life.)

The goalpost (and all of its variants) can be pulled by a tugboat instead of a tango, resulting in a period-2 spaceship.

### Half-squid

• Period-4 c/2 ship

### Owl

• Period-4 tagalong for two tugboats or schooners
• Nine variants are shown

### Sea urchin

• Period-4 c/2 ship

Two sea urchins can combine to produce a period-80 puffer. This puffer is the basis for the 40 up rake.

### Squid

• Period 4 c/2 ship

### Transformers

• Period 4 c/2 ship
• Front section appears to alternate between tugboats and schooners
• Two variants are shown

### Trawler

• Period-6 tagalong for two tugboats

### Glidermaker

• Period-8 c/2 ship
• Named after the sparks it produces, which resemble the glider from the Game of Life

### Turbulence

• Period 8 c/2 ship

Separating the two halves by an additional cell results in a period-196 puffer.

• Period-16 tagalong for two tugboats

• Period-16 tagalong for two tugboats

### Moonshine

• Period-18 c/2 ship
• Produces tub sparks

### Titan

• Period-26 c/2 ship
• 5th most common ship (after the tugboat, schooner, and two 2-tugboat chains)
• Emits one tub spark and two beehive sparks every 26 generations

The smallest known predecessor of the titan has only 11 cells.

Two titans can combine, resulting in a puffer that produces flares and blocks.

### Varangian guard

• Period-16 ship consisting of a byzantine and a schooner
• Produces beehive sparks

The Varangian guard can eat blocks:

### Symmetrical byzantine ship (SBS)

• Period-16 ship generated by two byzantines
• Tail half is invulnerable

The SBS can eat blocks, carriers, steeples, and other small patterns. It was discovered before the Varangian guard, and as a result, many of my engineered patterns (such as the rakes) make use of SBSs for cleaning up debris instead of Varangian guards. At some point, I will change this in order to reduce the size of these patterns.

The SBS can reflect a tugboat 180 degrees.

### Asymmetrical byzantine ship (ABS)

• Period-32 ship generated by two byzantines
• Tail half is invulnerable
• Produces accessible beehive sparks

The ABS can eat blocks, carriers, steeples, and other small patterns.

Two puffers made of ABSs are shown below: a nova puffer (left) and a feast puffer (right).

### Slowpoke

• Period-19 5c/19 ship

The slowpoke can eat blocks:

Two slowpokes can combine to produce a period-19 blinker puffer.

### Trilobite 1

• Period-4 c/4 ship

Tagalong:

### Trilobite 2

• Period-4 c/4 ship

Four tagalongs:

### Hawk

• Period-3 c/3 diagonal ship
• Smallest known diagonal ship

The hawk can stretch a diagonal line of chips:

The hawk supports many tagalongs, some of which can be found here. For example, its wings can be extended indefinitely:

### Eagle

• Period-3 c/3 diagonal ship

### Thunderbird

• Period-15 Hawk tagalong
• Emits beehive sparks
• Useful for constructing c/3 diagonal technology