I like this picture for several reasons, in just this one photo you can see so many things.
This is a historic common brick, not a pressed brick.
It’s a wide mortar joint typical of plaster covered or exposed rear exteroor walls of the time, about late 1800’s.
There are subtle signs of efflorescence salts around the edge of the mortar joint.
You can see the large chunks of quicklime in the mortar joint.