Nobody asked but here's my very complex headcanons & theories about how the cube species works within The Last Reality. Essentially, it's based on the idea all the members you see during the Cube invasion are part of one species at different evolution stages. (Think Pokemon evolution.)
So the literal cubes, like Kevin, are functionally the babies. They have very basic needs - energy consumption. They prepare for mass consumption by placing their runes, and more minor consumption by killing life forms. They can create corrupted versions of said lifeforms as a result of this, who work similarly to the next of two phases;
The Husks are sort of battle troops, and that's it. They're primarily for stifling all forces of resistance from the reality that's about to be dominated, and they're easily discardable due to a lower level of consciousness, primarily operating on the instinct to kill and harvest. They can also harvest energy, but it's less effective, and they cannot create Corruptions.
The Anthropormorphics, such as Cube Assassin and Geometrick, are what bring in the societal aspect of the species, having their own language and societal norms. Most will wear a little bit of clothing, or none at all. Most clothing is reserved for those of higher status, like Royalty, since they don't really need clothing, it's just there for aesthetics. They may ascend to royalty if chosen by a lone Royalty if their partner is no longer in the picture, either through abandonment or death.
Corruptions, aka the mirrored lifeforms, are similar to the Anthropromorphics except they do not have a cube-esque thing for a head, making them resemble Royalty. For this reason, they're often deployed to watch realities that have already been conquered instead of a part of the general society on the Mainland.
Royalty are ascended Anthropormorphics and are capable of creating more of the baby Cubes. They can also be created from Corruptions, but it's rare. There's normally two at a time, but there can be more if they so choose. They are the head of the hivemind created within Husks.
The reason that they collect energy is because that is what the species need to live instead of things like food, water, and shelter. There are defective Cubes, such as the Origin, that cannot hold onto their energy properly and release it in forms such as fire or electricity. They need to have a more stable flow of energy fed to them quite frequently, which is what the prison suit inside of his Seven suit is most likely for according to this little headcanon-theory, which is why he decided to keep it on instead of like... Not dressing like a prisoner everyday
