x = 23, y = 10, rule = B3/S23 2o$2o3$b2o17b2o$b2o17b2o3$21b2o$21b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 3 ZOOM 21 HEIGHT 400 SUPPRESS ]]
The blockade is a common formation of four blocks. 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.
