The Central Unit is a reoccurring sub boss in Metroid Dread. They appear right before you fight an EMMI to the death.
They get progressively get harder, but they’re fun little fights. In my opinion, the first battle was the hardest because you lack the abilities and energy tanks you have later in the game.
Once you kill one, your arm cannon temporarily becomes strong enough to kill an EMMI robot. Which is pretty darn cool.