The Extracerebrums are a race of green humanoids so named for their brains on the outside. The reason for this is that these brains serve as their own special defense mechanisms, as they are gelatinous like jello but strong and any hard rocks that are thrown at them will just bounce right off and away from them. They don't even feel it and are living proof that skulls are not the only way to protect a thinking brain. They also have psychic abilities to shoot electical energy bolts and other such direct energy defenses. They also have telekinesis and other such abilities. When humans look at them, they remind humans of 1950's science fiction movies, but they go on to explain how scientificly accurate those films were. They originate from the planet Cerebris.
The Semi-Cerebrums were related to and came from the same planet Cerebris as the Extracerebrums but were a seperate species on their own. They resemble the Extracerebrums but with smaller heads, wider hips and eyes with multipupiled features and were similar to frog and salamandar eyes. They also had skin which was a darker color of green. It was sometimes said that the relationship between these two species was similar to the relationship between humans and sasquatches. The mojarity of Extracerebrums don't even know for sure that Semi-Cerebrums actually exist, and are considered cryptids or mythical beings by them as well. They have build great and powerful cities underground and relay on geothermal energy to run them. But the technologies of both species were however basically between Type 1 and Type 2 and have successfully mastered Warp Drive and FTL travel and communications.