Holopneustes porosissimus, the short-spined urchin, is a species of sea urchin within the family Temnopleuridae. It is found in southern regions of Australia, excluding Tasmania.
Spines are red, the test is a greenish-grey, and the surface is covered with secondary tubercles. Diameter of up to 8 centimeters. It is common in waters from 0 - 30 meters in depth.