Deep underwater scene with glowing purple coral structures on a dark seabed, illuminated by bright blue sun rays and swimming fish.

These would be the dominant primary producers, evolving from single-celled ancestors that thrived in deeper, blue-light-penetrating waters. Unlike Earth's green plants which use chlorophyll A and B to absorb red and blue light (reflecting green), Cyanophyta Profunda would primarily use novel pigments optimized for blue light absorption, likely appearing **deep violet, black, or even an iridescent dark blue**. Their structures would be simple, filamentous or sheet-like mats initially, gradually forming more complex, branching thalli or encrusting structures on submerged rocks. See more