Ten new isoprenoids have been isolated from two marine sponges Ptilocaulis spiculifer and Axinella weltneri. P. spiculifer afforded three triterpenes, dihydroyardenone (1), abudinol B (2), muzitone (3) and two Ct3 and CI7 metabolites of abudinol, nakorone (4) and durgarnone (5). A. weltneri gave five new sodwanones, N-R (6 - 10). The structures of all new compounds were elucidated by spectroscopic analyses, mainly NMR data, and by chemical transformations to known compounds and degradations. The absolute configuration of several compounds was determined by optical measurements and comparison of the CD-eurves with those of several raspacionins. Several sodwanones were found to be cytotoxic.