Chrysochromulina pyramidosa is a unicellular marine haptophyte microalga in the genus Chrysochromulina, family Chrysochromulinaceae, class Prymnesiophyceae. The species epithet pyramidosa, meaning pyramid-shaped, refers to a pyramidal morphological feature — most likely a scale element or a distinctive cell shape — visible under electron microscopy. Within Chrysochromulina, the three-dimensional geometry of scales is a primary taxonomic character, and pyramid-shaped scales represent one of several distinctive scale forms distributed across the genus. C. pyramidosa has been documented from Norwegian and Swedish coastal marine environments, part of the extensive Scandinavian haptophyte biodiversity documented through systematic surveys of northern Atlantic coastal waters. These environments are characterized by cold, highly productive waters influenced by the North Atlantic Current and seasonal upwelling of nutrient-rich deep water. Chrysochromulina species including C. pyramidosa are common nanoplankton constituents in these systems, particularly during stratified summer conditions when nutrient depletion in surface waters selects for smaller, more efficient phytoplankton cells. Like other genus members, the species is presumed to employ both photosynthesis and potentially phagotrophic nutrition to sustain itself in variable nutritional environments. C. pyramidosa carries a conservation status of Not Evaluated under IUCN criteria. It represents one of the geometrically diverse scale forms documented within Chrysochromulina, contributing to the broader picture of haptophyte morphological evolution and diversity in temperate Atlantic marine systems.