Mosaicoolithus is an oogenus of fossil egg from Tiantai County, Zhejiang Province in China. Its classification is uncertain. The eggs are spherical, and 8.8 cm in diameter. It is distinctive for having irregular pore canals, sometimes filled by secondary shell units. Originally, it was classified as two separate oospecies of Spheroolithus: S. zhangtoucaoensis and S. jincunensis. However, these oospecies were synonymized and placed into a new oogenus by Wang et al. (2011).