A microscope is required to reliably distinguish "M. fulvoferrugineus" from "M. siccus". A saprobic fungus, "Marasmius fulvoferrugineus" fruits in groups or clusters on decaying leaves and humus in mixed woods. It is widely distributed in the southeastern USA, where it fruits in the summer and early fall. Fruit bodies contain an antifungal antibiotic named fulvoferruginin. This compound has a sesquiterpenoid carotane skeleton and has shows strong activity against Gram-positive bacteria and significant antifungal activity towards "Paecilomyces varioti".