What to watch
- It fits in a 3 x 3 bounding box with an empty center.
- Each live cell has the survival count it needs.
- It is a frequent natural object in random Life soups.
Still lifes
Tub
A four-cell still life shaped like a hollow diamond.
The tub is one of the smallest common still lifes. Its empty center is a clean example of why a dead cell needs exactly three neighbors before it is born.
- Category
- Still lifes
- Period
- 1
- Movement
- bounded
- Population
- 4 cells
- Bounding box
- 3 x 3
- Known since
- 1970
How to use it
Use it beside the beehive to show that an empty center does not imply a future birth.
Open the pattern in the lab, reduce the speed, and use single-step mode when a phase change is hard to see. The green preview marks births in the next generation; red outlines mark live cells that will die.