For a long time I assumed they were robots designed to resemble humans. But I realize than in Shake Before Using, Durandal confirms they are cyborgs. And Jason Jones once said the Simulacrums go insane from their "conversion."
So the BOBs on the autopsy tables in the pfhor ship are actually... !!!
But wait, later in M2, Durandal says that the pfhor stole the green uniforms from the science crew and put them on the simulacrums, so the science crew was left to run around naked. If the simulacrums were engineered from the bobs themselves, they'd already have their uniforms on them! I get the explosives and the brainwashing, but I don't understand the yellow blood and all of the "telltale signs" in the terminal robert blake shows us.
You don't operate on a human being and it suddenly mutates to have red eyes and two toes.
What are they? Hybrids? Where did they come from? A cybernetic organism doesn't just pop out of nothing!