On the outside an SAO resembles a human in every way, down to their hair follicles♦. The most obvious outside divergence from their human relatives is the gloss inherent to their flesh. The fact SAOs are hairless from the neck down.

On the inside, however, and the differences between SAOs and humans become considerable. An SAO’s muscle tissue is seemingly incapable of deteriorating, being denser and less prone to straining. Moreover, their muscles require less effort to keep toned. The SAO’s skeleton, although identical to a human’s in form and function, is wholly different in composition. Rather than be composed of calcium or collagen, their skeleton is instead a precisely tempered steel-titanium alloy built to withstand incredible amounts of stress and external heat. An SAO’s skeleton is also more flexible by about three degrees to better distribute force and adsorb shockwave. Natural tissue is affixed to this metallic apparatus much in the same way tissue is affixed to a human skeleton: via tendons. However, an SAO’s tendons are made of a durable meshed biological fiber that is similar in design to a coaxial cable.

Contrary to what their label synthetic anthropos operator suggests, other than their skeletal apparatus, SAOs have no synthetic parts. Their tissues, organs, glands, cells and, fundamentally, their DNA, is organic not artificial. In fact, their cells are a revolutionary enhancement of silicon that is biologically alive. What’s more, the greater forms (tissues, organs, etc.) made from these silicon builders are crystalline in composition.

SAOs possess the same vital organs as humans do. They’ve a brain, a pair of lungs, a heart and liver. Although an SAO does not digest food, they nevertheless have a digestive tract, including kidneys and a stomach. Any liquid ingested passes through these parts, so they are not vestigial or present just to support the proportions of the trunk and the organs therein. That said, an SAO does lack a rectum and, obviously, an anus. They have no reproductive organs or glands either. Therefore, they experience no sexual urge and haven’t need to mate. This reproductive absence is largely what fuels the misconception behind Sin the Tyrant as their creator. For if they cannot procreate, how do they generate?

An SAO’s blood resembles human blood by its texture and serves the like purpose. Still, it is darker than human blood (a shade darker than red wine) with a thicker consistency. Due to this thickness, blood transfers through their vascular system at a slower rate than a human’s. Combined with their cellular composition and conservation of energy, an SAO’s blood is the reason why they need very little sleep (roughly 8 hours a month). Because an SAO needs to maintain a regulatory body temperature (the ideal temp being within a degree of a human’s), this makes them warm-blooded rather than cold-blooded, though they are virtually unaffected by variances in temperature on Magnella due to their high tolerance for heat and cold.

Should a serious wound be made in a primary blood vessel, an SAO can bleed out. Although their blood moves slower and clots faster while their wounds heal quicker, a puncture made in the jugular vein, for example, cannot clot fast enough to check the bloodflow. Their blood’s thickness necessitates both their veins and arteries being bigger round to compensate for the additional pressure, which, relative to a human’s, discharges greater blood by volume out of an open channel. Hence, an SAO’s vulnerability to bleed-out.

♦SAO hair like human hair is made of keratin.