The bi-block is a common formation of two blocks and the smallest and most common[1]pseudo still life. Similar pseudo still lifes can be formed by considering any rectangular array of blocks, some of which are shown below.
Bi-blocks can be hassled to create oscillators, such as the p15 bi-block hassler.
The bi-block is about ¼ as common as the pond, the most common 8-bit strict still life. Compared to other strict still lifes, it it is more common than the ship-tie but less common than the long boat.[2] In odd orthogonal symmetries, bi-blocks are more common, as gliders in the same phase that collide in odd symmetry form a bi-block.
Counting both strict and pseudo still lifes, the tri-block is the 9th most common 12-bit still life, and it would rank third behind the ship-tie and table on table but ahead of the block on cap if it were strict. Unlike the bi-block, tri-blocks must form by chance.
