Chrysochromulina simplex is a haptophyte microalga in the family Prymnesiaceae, its specific epithet simplex (Latin: simple or plain) suggesting cells that lack elaborate ornamental scales compared with more complex congeners. Cells are biflagellate, bearing two unequal flagella and a haptonema of variable development. The cell surface, while bearing scales, may display less complex scale architecture than in other Chrysochromulina species. C. simplex inhabits marine and brackish coastal waters, with records from northern European seas including the coasts of Scandinavia. The genus Chrysochromulina is a major contributor to nanoplankton communities in cool, nutrient-enriched coastal waters, where haptophytes can dominate the phytoplankton biomass during seasonal stratification events. Mixotrophic capabilities documented in congeners allow flexible nutritional strategies in seasonally variable environments. The species has not been evaluated for conservation status by the IUCN and is listed as Not Evaluated. Free-living marine protists with cosmopolitan tendencies are generally resilient to localized environmental disturbances, though global ocean changes such as warming and acidification may shift community composition over longer timescales.