The Blueberry Stars Acropora is named for the scattered neon green stars or coral polyps that occur throughout the colony. These brightly colored polyps extend during the day time and contrast sharply with the blueberry colored branches. A very unusual color combination for a branching Acropora. This A. echinata or A. cardus was originally thought to be a Dragon type Acropora, but the elongated branchlets are more structured and ordered.