Nudibranchs and other molluscs.
Molluscs can have a large variety of body forms and there are many known species (over 8000). 6 of the 7 classes are recorded from shallow Australian seas.
Gastropod molluscs are the most common and are found on the intertidal zone, most of them feed on small algae however some are predatory.
Nudibranchs are the most colourful and found in a variety of shapes, colours and sizes. There are 300 species found in Australia with many more to be discovered. They generally specialist feeders that feed on the variety of sessile organisms.