The Spheroids are pink semi-sentient ball-like creatures on the planet Spheron I. Their history and language remain unknown to humans. Their leaders are known as "Brain Balls", who are the only ones who know how to talk. The Spheroids appear to attack by hitting and bouncing on their target. They lost their planet in a war against Earth and had to relocate. A sighting of them in Into the Wild Green Yonder confirms that they are not extinct.
The Spherons were likely a very resilient race, considering that their home world had no natural resources of which to speak.