The Republic of Maldives' black marine sponge Hyrtios erecta has been found to contain three cancer cell-line inhibitory pentacyclic sesterterpenes designated sesterstatins 1-3 (2-4). One of the sesterterpenes, sesterstatin 2, specifically inhibited the Gram-positive opportunist Staphylococcus aureus. All three of the P-388 lymphocytic-leukemia-active (ED50 0.46 to 4.3 micrograms/mL) sesterstatins were obtained in trace quantities (3.0 x 10-7 to 5.4 x 10-7% yields) and represent structural variations on the more usual scalarin-type porifera sesterterpenes. The structures were elucidated by highfield (500 MHz) 2D NMR techniques augmented by HRMS results.