Three new sesterterpene sulfates, halisulfates 8-10 (1-3), were isolated from the Australian sponge Darwinella australensis. The structures of these compounds were determined by combined spectroscopic methods. The stereochemistry of the decalin moiety was assigned on the basis of NMR interpretations. Halisulfates 9 and 10 inhibited cell division of sea urchin eggs in moderate concentration.