Discovery of the holotype of the supposed sponge Cyathospongia(?) eozoica Matthew in the collections of the New Brunswick Museum completes a search for two doubtful Precambrian "sponges" described by Matthew almost a century ago. The organic nature of C.(?) eozoica had been questioned almost since its publication in 1890, but the specimen had been inaccessible. Examination of the holotype of C.(?) eozoica suggests the "spicules" from the Green Head Group of Saint John are probably a boxwork-like weathering pattern and are not organic.