As compounds from a calcareous sponge, Leucetta sp., of the Coral Sea, we isolated a series of novel naamidine-type alkaloids, 6-10, which are oxidized at a single benzylic position. We also report on the first marine, mixed-ligand metal complex 5 and on the first natural metal complexes 3 and 4 derived from classical naamidines, i.e., 1 and 2. The latter are also present in free form in the sponge.