Three novel antimicrobial metabolites have been isolated from the Pacific sponge Agelas sp. Two of the metabolites, ageline A (4a) and ageline B (5a), are quarternary 9-methyladenine salts of diterpenes. The third and minor metabolite was shown to be agelasidine A (6), a sesquiterpenoid derivative of taurocyamine. The structures of ageline A and ageline B were elucidated by interpretation of spectral data with particular emphasis on 13C NMR correlations. The agelines are mild ichthyotoxins and show moderate antimicrobial activities.