|Nobody here but us stones....|
Lithops use camouflage as their primary defense. Each species and subspecies lives in a uniquely colored and textured environment in southern Africa. I could not hope to duplicate the exquisite camouflage ability of Lithops in the wild, but I can manage to hint at it:
And now for something completely different...a Mammillaria gracilis, trying not to be seen.
Spines and camouflage, awesome!