The Alexandri Sea Urchin (Temnopleurus alexandri) is a tropical sea urchin species that is found in the waters of Australia and belongs to the family Temnopleuridae. In Australia it is distributed from Fremantle in Western Australia around the north to Port Hacking in New South Wales. This species can be found amongst seaweeds, on shell grit substrates and rocky reefs. This species often camouflages itself with detritus and as a result is often over looked by divers. The spine tips of this species can vary in colour and can be white/purple, green/brown, green/olive, green/purple or white/maroon. The primary spines reach a maximum length of approximately 1.2cm and this species is known to feed on algae and seaweeds.
The Alexandri Sea Urchin Temnopleurus alexandri grows to a maximum width of approximately 10 cm.