Pre-block (or latent block), a triomino, is a common parent of the block. Given its compactness and distinctive form, it is a recognizable component of many other patterns, such as boat, ship, aircraft carrier, block and glider or snake; a mirrored pair comprise one phase of a beacon.
The pre-block is similar to the tub, boat, beehive and such in the sense that it can be augmented with items like tails, as in eater 1 and integral sign.
In terms of its 3 cells, it is the smallest induction coil.
A glider hitting a pre-block can produce a LWSS or MWSS; this is detailed in pre-pre-block.
Pre-block can be infinitely extended, as illustrated by the following: