Sorry, this one I can't give away … it is unique to the story. You'll have to read the book!
The atom: the meaning commonly relates to science, which is prevalent in this story (or, in this case, the consequences of science).
The Vitruvian-Man-like central image represents science in general, and the Exoskeleton in particular.
The triquetra: Sometimes called the "trinity knot," this symbol has referred to the Christian trinity, and the Wiccan tri-goddess. There are themes in this book that can be associated with the latter.
Death: a strong theme in the story. Perhaps we shouldn't fear it as much as we do ...
Eye of Providence: also known as the "eye of God," this symbol represents God keeping an eye over humankind.
Nazi Dark Sun: It is an occult and esoteric symbol based on a "sun wheel" mosaic laid into the floor of Wewelsburg Castle during the Nazi era.
The cover was designed by William Renehan, Editor, of Dark Hall Press. I had some input for tweaks, but otherwise I was quite pleased from the first draft. I think he did a great job coming up with something that encompassed the wide variety of themes that run through Exoskeleton.
I am frequently asked about the symbols, so I've identified them and given a short description of each in the figure. Each one is connected to the story in some way -- some more strongly than others.
The Taijitu: also known as the yin and yang symbol. It represents the ever-evolving struggle between dark and light, good and evil, and the convolution of these things into one entity.
The Pentagram: With a single point of the star on the top, this is the Christian symbol for the five senses. When the star is rotated so that two point are on the top, it represents evil and attracts sinister forces by disrupting the proper order of the world. It is a sign of the triumph of matter over spirit. Both representations are relevant in Exoskeleton.