A new sesquiterpene derivative named mochiquinone (1) was isolated from the Caribbean gorgonian coral Pseudopterogorgia rigida collected off northeastern Venezuela, along with the known compounds, alpha-curcumene, (-)-curcuphenol, (-)-curcuquinone, and (-)-curcuhydroquinone. The structure of the new compound was determined by spectroscopic analysis of its acetylated derivative and comparison with known compounds.