With Smalltalks image approach you save the whole state of your "object oriented world" to disk and continue later at the same point of execution where you left. Some objects are part of the standard image since the 1970s which makes Smalltalk images software artefacts that are maintained since a long time.
Nonetheless it also makes sense to bootstrap new images right from the start and (as I already reported) the Pharo community is working on that. Now there is yet another step done for this as you can read and now also try here.
Note that the boostrapped image is already in Spur format.