The Purple Sea Urchin (Heliocidaris erythrogramma) is a very common intertidal species that belongs to the family Echinometridae. It can be found from Shark Bay in Western Australia around the south coast of Australia (including Tasmania) to the waters of southern Queensland. This species varies significantly in colour and individuals from two different areas may appear to be completely separate species. The colour of the spines can vary between dark purple, grey, brown, pink, cream, orange and pale green. The secondary spines are similar in colour however are thinner and shorter.
This species is known to feed on algae, ascidians, bryozoans, sponges, seaweeds, seagrass and encrusting organisms found on rocky reefs and platforms. The Purple Sea Urchin (Heliocidaris erythrogramma) grows to a maximum width of approximately 10cm.