Along with two known cheilanthane sesterterpene lactones, 1 and 2, eight new related sesterterpenes (3-10) and two new nor-sesterterpenes (11 and 12) have been isolated from the New Caledonian marine sponge Petrosaspongia nigra Bergquist 1995 (new genus, new species). Their structures were determined from 1D and 2D NMR studies and mass spectral data. They exhibited cytoxicity against the NSCLC-N6 human bronchopulmunary non-small-cell-lung carcinoma cell lines.