This page lists description quotes for the Sentry Golem mob, which originate from various sources. Sources are in game from the Book of Lore item (in the original The Aether mod) or officially as word of god from the developers.
"The Ancient Labyrinths that make up the Valkyrie’s precious Vaults house many mysterious machines known as Sentries.
"These Mechanical Constructs are styled to look like living creatures, but act more like self driven tools, each having a distinct purpose that it is restricted to.
"An example of this is the Sentry Golem, the most humanoid of the Sentries, it’s purpose can vary depending on the model, but this one in particular is designed as a guard, so it has the ability to identify threats and neutralize them accordingly. It does this through what is known as a “Mind Core”, a Cube inside the chest of the Sentry that can somehow process complex inputs like vision and calculate outcomes, very similar to how a biological brain works.
"The Mind Core is also responsible for the distribution of Ambrosium impulses through the Body, which control its limbs and different processes, for example the Sentry Golem can generate explosives from its back, but the parts used for this are only turned on when the Mind Core tells it to, meaning the Sentries waste very little energy.
"Another interesting aspect of the Sentries is how they move. Their joints are made up of supercooled Gravitite gears, surrounded by Icestone. These allow for fluid movement without parts grinding against each other, but also means the joints are incredibly weak, being broken apart quite easily.
"Further study of the Sentries also reveals that they are not of Valkyrie design, but are too ancient to be the product of Angel research, so their origin is left a mystery."