Red Algae - Phylum Rhodophyta

Red algae come in a variety of shades of red due to additional red protein pigments in the fronds. The red colour is not uniform and some species are purple, mauve, orange or even yellow.
These pigments allow the red algae to grow at far greater depths than the green and brown algae. Red algae can occur down to 200 metres.
Red algae have a wide variety of forms, including encrusting, string-like, tube-like, filamentous and flat sheets. Red algae rarely are important in rocky shore or reef communities. They prefer deeper waters.
Some examples of Red Algae are:
Coralline seaweed, Corallina officinalis

Encrusting Corallines, Coralline Algae

Macroalgae and Microalgae
The large algae, or macroalgae, are the largest and most obvious forms of algae that we can easily see.
However, there are the microalgae, and just hatched spores of all algae, that coat the floor of many rockshore pools and surfaces. This forms one of the most important food sources for algae-eating molluscs. We call these algae-eating animals herbivores.
Much microalgae also drifts around in the ocean currents as part of the plankton. This is a major source of food for many oceanic and seashore animals and their juvenile planktonic stages.