Five new metabolites have been isolated from a lyngbyastatin 1- and dolastatin 12-producing assemblage of Lyngbya majuscula and Schizothrix calcicola collected at Tumon Bay, Guam. Structure elucidation employed 2D NMR techniques and chemical derivatization. These compounds have been assigned the trivial names tumonoic acids A (2), B (1), and C (5); methyl tumonoate A (3), and methyl tumonoate B (4). Compounds 1 and 4 were also found in a lyngbyastatin 1-producing strain of L. majuscula from Guam.