Because of their great internal 'wait' (weight X negative velocity) they create these unique three-dimensional extremely dense gravitational fields which look more like what you and I would describe as rocks, but are really stationary fragments of invisible geological force fields.
Since they have such a timeless inherent inertia ( invisible self-contained inner movement ) they have often been perceived as merely motionless and inanimate but this is not the case. They rock ! They roll. When their faults are exposed they make faces, They lie down in bedding planes, and 'split' along certain lines and shift, fall, slide and drop whenever they get a chance, just to mention a few examples. If you've ever carefully studied a rock on one, you will know they travel around quite a bit on a 'freeze thaw cycle'.
'Rock on a freeze thaw cycle'
It may not seem like its moving, but it is.