The blockade is a common formation of four blocks and is one of the familiar fours. A common evolutionary sequence that leads to its formation is known as lumps of muck, which can be seen by letting the stairstep hexomino evolve.
A half-blockade is an 8-bit constellation consisting of two blocks with two empty rows separating them, offset by one cell. It most commonly forms as part of a blockade, but there are ways it can form by itself, such as the heptomino that is the orthogonally connected part of the MWSS in its less dense phase.
