Alternatives: micro-sphere / pl∙ micro-spheres
1. A microscopic ball.
2. A small radius of action or influence, such as a single person's reach or power in the society, or the electric effects of a single molecule limited to its closest proximity.
Mam was plaintively recounting their travails with the social custodian lady, and Doctor Barton continued pondering stiffly. He sympathetically muttered that if it were in his power to abate a mere half a per cent of the worriments in his own microsphere, the world would look different. But even he himself supposed he had to stay away from certain kinds of people whenever possible. Or at least to keep them at arm's length. And he definitely wasn't omnipotent. (Context: Dr∙ Barton thinks hard about how he could help the Boleks harassed by the administrative oversight of their family life. He makes it clear upfront that fighting dysfunctional state authorities will not be easy. Source: J∙ Okram - The Mystery of the Rammed Key.)