RGB

The RGBs were an rock-like alien species hailing from the realms beyond the Moleculands.

Physiology
The RGBS resembled large lumpy rock-like humanoids.

History
The RGBs were a mighty race and one of many species Krigari the Iron-Handed ruthlessly slaughtered in his path for glory.

Source

 * Astro City 017 (2014)