An examination of the digestive gland extracts from two color variants of the circumtropical sea hare Aplysia dactylomela, collected off the Eastern Cape coast of South Africa, yielded four new halogenated sesquiterpenes: algoane (1), 1-deacetoxyalgoane (2), 1-deacetoxy-8-deoxyalgoane (3), and ibhayinol (4). The known sesquiterpenes, nidificene (5) and prepacifenol epoxide (6), were also isolated from the A. dactylomela extracts. Standard spectroscopic techniques were used to determine the structures of compounds 1-6, with a single-crystal X-ray diffraction experiment establishing the structure of 1 and providing the absolute stereochemistry of this compound.