Endocarpon pusillum . A. The lichen E. pusillum. B. The isolated mycobiont and phycobiont . C. Cross section of a perithecium with hymenial algal cells inside. D. Cross section of a thallus under scanning electron microscopy (SEM). E. The algal layer (SEM). F. An algal cell is clasped and surrounded by some hyphae (SEM).